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Issued  October  9, 1912. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  158. 

A.  D.  M  ELY  IN,  CHIEF  OF  BUREAU. 


;HE  ROUNDWORMS  OF  DOMESTIC  SWINE, 


WITH  SPECIAL  REFERENCE  TO  TWO  SPECIES 
PARASITIC  IN  THE  STOMACH. 


BY 


WINTHROP  D.  FOSTER, 

Junior  Zoologist,  Zoological  Division. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 
1912. 


Bui.   168,  Bureau  of  Animal  Industry,  U.  S.  Dept    of  Agriculture. 


PLATE  I. 


Hainas.del  __ 

A  PORTION  OF  THE  PYLORIC  END  OF  A  HOG'S  STOMACH.  INFESTED  WITH 
AROUENNA  STRONQYLINA  AND  PHYSOCEPHALUS  SEXALATUS.  (NATURAL  SIZE.) 

The  worms  appear  as  fine  red  lines  partly  buried  in  a  yellow  glairy  mass  of  necrotic  tissue. 
Ulcers  are  found  underneath  this  necrotic  tissue. 


Ksm-.l  (  X-II.I..T  9,  1912. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  158. 

A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


THE  ROUNDWORMS  OF  DOMESTIC  SWINE, 

WITH  SPECIAL  REFERENCE  TO  TWO  SPECIES 
PARASITIC  IN  THE  STOMACH. 


BY 

WINTHROP  D.  FOSTER, 

Junior  Zoologist,  Zoological  Division. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 
1912. 


BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  A.  D.  MELVIN. 

Assistant  Chief:  A.  M.  FARRINGTON. 

Chief  Clerk:  CHARLES  C.  CARROLL. 

Animal  Husbandry  Division:  GEORGE  M.  ROMMEL,  chief. 

Biochemic  Division:  M.  DORSET,  chief. 

Dairy  Division:  B.  H.  RAWL,  chief. 

Field  Inspection  Division:  R.  A.  RAMSAY,  chief. 

Meat  Inspection  Division:  RICE  P.  STEDDOM,  chief. 

Pathological  Division:  JOHN  R.  MOHLER,  chief. 

Quarantine  Division:  RICHARD  W.  HICKMAN,  chief. 

Zoological  Division:  B.  H.  RANSOM,  chief. 

Experiment  Station:  E.  C.  SCHROEDER,  superintendent. 

Editor:  JAMES  M.  PICKENS. 

ZOOLOGICAL   DIVISION. 

Chief:  B.  H.  RANSOM. 

Assistant  zoologists:  ALBERT  HASSALL,  HARRY  W.  GRAYBILL,  MAURICE  C.  HALL,  and 

HOWARD  CRAWLEY. 
Junior  zoologist:  WINTHROP  D.  FOSTER. 

2 


LETTER  OF  TRANSMITTAL. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

Washington,  D.  C.,  July  2,  1912. 

SIR:  I  have  the  honor  to  transmit  herewith  a  manuscript  entitled 
"The  Roundworms  of  Domestic  Swine,  with  Special  Reference  to 
Two  Species  Parasitic  hi  the  Stomach,"  by  Mr.  W.  D.  Foster,  of  the 
Zoological  Division  of  this  bureau.  I  respectfully  recommend  its 
publication  in  the  bulletin  series  of  the  bureau. 

The  paper  deals  particularly  with  two  species  of  nematodes  which 
have  recently  attracted  considerable  attention  in  connection  with 
the  Federal  meat  inspection.  The  parasites  are  shown  to  be  of  wide 
distribution  and  frequency  of  occurrence  hi  American  swine,  and  they 
are  a  source  of  possible  serious  injury  to  these  animals. 

The  illustrations  were  drawn  by  Mr.  W.  S.  D.  Haines,  of  this 
bureau. 

Respectfully, 

A.  D.  MELVIN, 

Chief  of  Bureau. 
Hon.  JAMES  WILSON, 

Secretary  of  Agriculture. 

3 


CONTENTS. 


Page. 

Summary 7 

Introduction 8 

Family  Filariidse 9 

Subfamily  Arduenninac 9 

Genus  Arduenna 9 

Arduenna  slrongylina 10 

Arduenna  dentata 20 

Genua  Physocephalus 21 

Physocephalus  sexalatus 21 

Comparison  of  Physocephalus  sexalatus  and  Arduenna  strongylina 31 

Other  species  referred  to  Physocephalus  sexalatus 31 

Distribution  of  Arduenna  strongylina  and  Physocephalus  sexalatus  in  the  United 

States , 32 

Relative  frequency  of  the  two  species 34 

Lesions  associated  with  Arduenna  strongylina,  Arduenna  dentata,  and  Physo- 
cephalus sexalatus 34 

Life  history 3g 

Preventive  measures .' 37 

Medicinal  treatment 37 

Key  to  the  round  worms  parasitic  in  domestic  swine 38 

Classified  list  of  the  roundworms  parasitic  in  domestic  swine 41 

Bibliography 45 

5 


ILLUSTRATIONS. 


PLATE. 

PLATE  I.  A  portion  of  the  pyloric  end  of  a  hog's  stomach,  infested  with  Arduenna 

strongylina  and  Physocephalus  sexalatus Frontispiece 

TEXT   FIGURES. 

Page. 

FIG.    1.  Arduenna  strongylina.    Median  view  of  cephalic  end 10 

2.  Arduenna  strongylina.    Burea  of  male,  ventral  view 11 

3.  Arduenna  strongylina.    Posterior  end  of  body  of  male,  viewed  from  right 

side 12 

4.  Arduenna  strongylina.     Posterior  end  of  body  of  female,  viewed  from 

leftside 12 

5.  Arduenna  strongylina.     Ventral  view  of  middle  of  body  of  female. ...  13 

6.  Arduenna  strongylina.    Lateral  view  of  egg  removed  from  a  ruptured 

uterus 13 

7.  Arduenna  strongylina.    Short  spicule  with  retractor  muscles,  viewed 

from  right  side 14 

8.  Arduenna  strongylina.    Posterior  end  of  body  of  male,  viewed  from 

leftside 14 

9.  Arduenna  strongylina.    Cross  section  through  body  of  female  in  the 

region  of  the  vulva 15 

10.  Arduenna  strongylina.    General  view  of  body  of  male  from  right  side.  15 

11.  Arduenna  strongylina.    General  view  of  body  of  female  from  left  side .  16 

12.  Arduenna  strongylina.     Cephalic  end 17 

13.  Arduenna  strongylina.    Bursa  of  male,  ventral  view 17 

14.  Physocephalus  sexalatus.    Lateral  view  of  cephalic  end 18 

15.  Physocephalus  sexalatus.    Lateral  view  of  cephalic  end 18 

16.  Arduenna  dentata.    Median  view  of  cephalic  end 20 

17.  Arduenna  dentata.     Bursa  of  male,  ventral  view 20 

18.  Physocephalus  sexalatus.     Dorsal  view  of  anterior  end  of  body 22 

19.  Physocephalus  sexalatus.     Posterior  end  of  body  of  male 23 

20.  Physocephalus  sexalatus.     Bursa  of  male,  viewed  from  left  side 24 

21.  Physocephalus  sexalatus.    Posterior  end  of  body  of  female,  ventral 

view 25 

22.  Physocephalus  sexalatus.    Ventral  view  of  body  of  female  in  the  region 

of  the  vulva 25 

23.  Physocephalus  sexalatus.    Lateral  view  of  egg  removed  from  a  ruptured 

uterus 26 

24.  Physocephalus  sexalatus.    Bursa  of  male,  ventral  view 26 

25.  Physocephalus  sexalatus.    Cross  section  through  anterior  part  of  body. .  27 

26.  Physocephalus  sexalatus.    Ventral  view  of  body  of  female 27 

27.  Physocephalus  sexalatus.    Lateral  view  of  anterior  end  of  body 28 

28.  Physocephalus  sexalatus.    General  view  of  body  of  male 29 


THE  ROUNDWORMS  OF  DOMESTIC  SWINE,  WITH  SPECIAL  REF- 
ERENCE TO  TWO  SPECIES  PARASITIC  IN  THE  STOMACH. 


SUMMARY. 

Two  species  of  roundworms  belonging  to  the  family  Filariidse,  of  particular  interest 
to  helminthologists  and  veterinarians  on  account  of  their  wide  distribution  and  fre- 
quency of  occurrence  in  American  swine  and  the  possibility  that  they  may  cause 
serious  injury  to  their  host,  are  given  special  consideration  in  this  paper. 

One  of  these  species,  identified  as  Spiroptera  strongylina,  has  recently  been  placed 
in  a  new  genus,  Arduenna,  of  which  it  is  the  type,  and  several  errors  regarding  the 
anatomy  of  this  parasite  have  been  corrected.  Another  species,  Arduenna  dentata, 
has  been  found  in  China  associated  with  Arduenna  strongylina,  and  although  not  yet 
reported  in  American  swine  is  mentioned  in  this  connection,  as  further  investigation 
may  reveal  its  presence  in  this  country. 

Arduenna  strongylina  is  much  more  common  in  American  swine  than  it  is  said  to 
be  in  European  swine,  and  has  been  found  abundantly  in  the  slaughterhouses  at  St. 
Louis,  Chicago,  South  Omaha,  and  Kansas  City,  and  has  also  been  collected  at  Ben- 
ning,  D.  C.,  and  Bethesda,  Md. 

Specimens  of  hogs'  stomachs  received  from  Chicago  showed  the  worms  deeply 
fastened  in'  the  submucosa  or  embedded  in  necrotic  tissue  near  which  were  deep 
ulcers.  The  condition  suggested  infection  with  Bacillus  necrophorus,  the  inoculation 
of  which  might  easily  result  from  the  burrowing  of  the  worms;  however,  owing  to  the 
sterile  condition  of  the  specimens  received,  this  could  not  be  satisfactorily  demon- 
strated. A  similar  diseased  condition  of  the  stomachs  of  hogs  in  Europe  is  attributed 
by  Von  Ratz  (1899d)'  to  infection  with  Arduenna  strongylina.  Under  the  circum- 
stances the  worm  should  be  regarded  with  grave  suspicion,  and  general  prophylactic 
measures  for  the  prevention  of  the  spread  of  infection  are  suggested. 

Commonly  associated  with  Arduenna  strongylina  in  this  country  is  another  worm, 
identified  as  Physocephalus  sexalatus,  first  described  by  Molin  (1860b)  from  specimens 
from  the  peccary  (Dicotyles  labiatus)  from  Brazil;  also  found  by  him  associated  with 
Arduenna  strongylina  from  the  wild  boar  in  Germany.  It  is  also  reported  by  Von 
Linstow  (1879b)  (who  apparently  mistook  this  species  for  Arduenna  strongylina) 
and  Piana  (1897e),  from  Europe,  and  by  Railliet  and-  Henry  (1911b),  from  Madagascar 
and  Indo-China,  in  the  former  case  associated  with  a  severe  gastritis.  Seurat  (1912) 
has  recently  reported  this  species  from  the  ass  and  dromedary  in  Algeria,  but  his 
statements  would  seem  to  require  confirmation. 

According  to  the  writer's  experience,  Physocephalus  sexalatus  is  almost  as  widely 
distributed  as  Arduenna  strongylina,  since  out  of  eight  lots  of  specimens  of  the  latter 
species,  specimens  of  Physocephalus  sexalatus  were  found  in  all  but  one.  In  a  mixed 
infection,  however,  it  has  never  been  found  as  abundantly  as  Arduenna  strongylina. 
This  worm  has  apparently  the  same  habit  of  injuring  the  mucosa  as  has  Arduenna 
strongylina,  as  both  species  were  found  in  the  same  necrotic  tissue  in  a  hog's  stomach. 
It  must  therefore  be  considered  only  less  dangerous  because  it  is  less  abundant,  and 
should  be  subject  to  the  same  treatment  suggested  for  infestation  with  Arduenna 
strongylina. 

'  References  to  literature  will  be  found  in  bibliography  at  end  of  bulletin. 


8  THE  ROUNDWORMS   OF   DOMESTIC   SWINE. 

Nothing  is  known  in  regard  to  the  life  cycle  of  these  parasites,  but  their  wide  distri- 
bution and  frequency  of  occurrence  suggest  a  simple  life  history  without  an  interme- 
diate host.  The  fact  that  the  eggshells  of  both  species  are  relatively  thick  would 
seem  to  indicate  that  the  embryos  are  not  liberated  until  the  shell  is  dissolved  by  the 
gastric  juice  of  the  host.  From  the  fact  that  the  embryos  are  fairly  well  developed 
before  oviposition,  it  may  be  inferred  that  the  eggs  require  but  a  short  period  of  incu- 
bation. 

Following  the  discussion  of  the  two  species  is  a  key  for  use  in  the  identification  of 
round  worms  parasitic  in  swine;  also  a  list  of  these  parasites  classified  according  to  their 
zoological  position. 

INTRODUCTION. 

Nematodes  occurring  in  the  stomach  are  commonly  present  among 
swine  in  the  United  States.  These  have  usually  been  considered  by 
veterinarians,  pathologists,  and  others  who  have  had  occasion  to 
mention  them  as  belonging  to  the  species  Spiroptera  strongylina 
Rudolphi,  1819,  although  some  have  expressed  a  doubt  as  to  the  cor- 
rectness of  the  identification.  In  addition  to  the  forms  which  have 
been  identified  as  Spiroptera  strongylina,  Hassall  and  Stiles  (1892a) 
have  described  a  species  named  by  them  Strongylus  rubidus,  and 
which  has  since  been  collected  from  domestic  swine  in  Europe. 

Recently  a  zoological  study  of  specimens  of  nematodes  in  the  hel- 
minthological  collection  of  the  Bureau  of  Animal  Industry,  collected 
from  the  stomachs  of  hogs  in  various  parts  of  the  United  States,  was 
undertaken  by  the  present  writer,  largely  as  a  result  of  reports  from 
inspectors  relative  to  the  prevalence  of  nematodes  in  the  stomachs 
of  swine,  Drs.  J.  J.  Brougham  and  T.  B.  Pote,  of  the  St.  Louis  station, 
having  been  among  the  first  in  the  Federal  service  to  give  attention  to 
the  subject  from  the  standpoint  of  meat  inspection.  As  a  result  of  this 
study  and  of  a  comparison  of  these  specimens  with  specimens  of 
Spiroptera  strongylina  received  from  Europe,  the  conclusion  has  been 
reached  that  in  several  particulars  the  descriptions  of  Spiroptera 
strongylina  commonly  given  by  European  writers  are  in  error,  and 
that  the  forms  commonly  identified  as  Spiroptera  strongylina  represent 
two  distinct  species,  one  of  them  Spiroptera  strongylina,  the  other  cor- 
responding to  Physocephalus  sexalatus  (Molin,  1860)  Diesing,  1861, 
hitherto  considered  a  rare  parasite  and  until  recently  reported  only 
once  for  domestic  swine. 

According  to  Stiles  and  Hassall  (1905b),  the  genus  Spiroptera  is 
preempted  by  the  genus  Acuaria  Bremser,  1811,  whose  type  is 
anthuris.  This  species  is  also  the  type  of  Dispharagus  Dujardin,  1845, 
a  genus  based  largely  on  certain  nematodes  of  birds  and  not  found  in 
mammals.  According  to  this  ruling,  the  genus  Acuaria  is  confined  to 
certain  parasites  of  birds  and  fishes  characterized  by  a  differentiation 
in  the  structure  of  the  esophagus.  As  Spiroptera  strongylina  does 
not  conform  to  the  type  of  Acuaria  or  the  characteristics  of  the  genus, 
a  new  genus  to  include  these  forms  is  necessary.  This  deficiency  has 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE.  9 

been  supplied  by  the  creation  of  a  new  genus,  Arduenna,  by  Railliet 
and  Henry  (1911),  Spiroptera  strongylina  being  taken  as  the  type. 
Both  Arduenna  and  PJiysocephalus,  together  with  Simondsia  paradoxa, 
belong  in  the  family  Filariidse,1  and  are  included  by  Railliet  and 
Henry  (191  Ib)  in  the  new  subfamily  Arduenninae. 

FAMILY  FILARIIDSE,  GLAUS,  1885. 

FAMILY  DIAGNOSIS. — Nematoda:  Body  long,  filiform.  Mouth  surrounded  with 
papillae,  or  provided  with  two  lips.  Esophagus  slender,  without  posterior  bulb. 
Males  with  a  single  spicule  or  with  two  unequal  spicules.  Females  with  two  ovaries; 
vulva  usually  in  front  of  the  middle  of  the  body.  Usually  ovoviviparous.  Develop- 
ment in  many  cases  requires  an  intermediate  host. 

TYPE  GENUS.— Filaria  Muller,  1787. 

Subftmaily   AJIDTJENNIN^E    Railliet   tmd   Henry,  1911. 

SUBFAMILY  DIAGNOSIS. — Filariidae:  Mouth  with  two  lateral  lips  leading  into  a 
pharynx  marked  with  cuticular  ridges  in  the  form  of  spirals  or  rings.  Spicules 
unequal,  the  longer  several  times  the  length  of  the  shorter.  Four  pairs  of  preanal 
papillae.  Eggs  containing  embryos  when  oviposited. 

TYPE  GENUS. — Arduenna  Railliet  and  Henry,  1911. 

Genus  ARDUENNA  Railliet  and  Henry,  1911. 

GENERIC  DIAGNOSIS. — Filariidee:  Body  subcylindrical,  attenuated  anteriorly, 
posteriorly  somewhat  broader,  usually  curved  in  a  semicircle,  marked  by  a  narrow, 
longitudinal  cuticular  wing  on  the  left  side,  extending  nearly  the  length  of  the  body. 
Cuticle  densely  striated  transversely.  Mouth  with  two  lateral  lips,  each  lip  with 
three  lobes,  leading  into  a  small  buccal  capsule  containing  two  lateral  teeth,  and  fol- 
lowed by  a  cylindrical  pharynx  marked  with  cuticular  ridges  forming  a  series  of  spirals. 
Esophagus  continuous,  gradually  broadening  posteriorly  and  occupying  from  one- 
fourth  to  one-third  of  the  body  length.  Caudal  end  of  the  male  curved  in  a  single 
turn.  Bursa  asymmetrical,  the  right  bursal  wing  being  broader  than  the  left  wing, 
furnished  with  five  pairs  of  stalked  papillae  asymmetrically  arranged,  of  which  one 
pair  is  preanal,  three  pairs  are  adanal,  and  the  fourth  pair  is  postanal.  Bursal  mem- 
brane marked  with  longitudinal  and  transverse  striae,  giving  it  a  wrinkled  appearance. 
Anus  surrounded  by  a  cuticular  thickening,  serrated  on  the  outside  edge.  Spicules 
long  and  very  unequal,  the  longer  five  to  seven  times  the  length  of  the  shorter.  Vulva 
anterior  of  the  middle  of  the  body.  Eggs  with  thick  shells  containing  embryos  at  the 
moment  of  oviposition.  Parasitic  in  the  stomachs  of  Suidse. 

TYPE  SPECIES:  Arduenna  strongylina  (Rudolphi,  1819),  Railliet  and  Henry,  1911. 

»  Diesing  (1861a)  proposed  the  family  name  Spiruridea  for  a  group  of  nematodes  distinguished  from 
FUaria  by  the  curl  or  spiral  twist  of  the  tail  of  the  male.  This  family  is  not  accepted  by  most  recent  writers 
on  the  ground  that  it  is  not  based  on  sufficiently  characteristic  morphological  features,  and  that  the  name 
does  not  conform  to  the  rules  of  zoological  nomenclature.  Oerley(18S5a),  Leiper  (1908),  and  Railliet  and 
Henry  (1911b)  use  the  name  Spiraridae,  apparently  modifying  Diesing's  (1861a)  family  name  Spiruridea 
to  conform  to  the  present  zoological  nomenclature.  The  family  name  Spiropterldae  Is  proposed  by  Leroer 
(1911). 

Owing,  however,  to  the  apparent  invalidity  of  the  name  Spiroptera,  the  present  writer  prefers  not  to  use 
either  the  family  name  Spiruridse  or  Spiropteridse,  and  although  it  is  evident  that  the  genera  Arduenna 
and  PJiysocephalus,  and  other  genera  as  well,  will  ultimately  be  separated  from  the  Filariidse,  it  is  not  con- 
sidered desirable  to  attempt  such  a  revision  until  a  more  careful  study  has  been  made  of  the  various  species 
involved.  In  the  present  paper,  therefore,  A  rduenna  and  Physoccphalus  are  retained  in  the  family  Filariidse 
but  included  under  the  subfamily  Arduenninse,  Railliet  and  Henry,  1911. 

52865°— Bull.  158—12 2 


10 


THE   BOUNDWORMS   OF   DOMESTIC   SWINE. 


Arduenna  strongylina  (Rudolphi,  1819)  Railliet  and  Henry,  1911. 

1819:  Spiroptera  strongylina  Rudolphi,  1819a,  p.  23. 

1819:  Spiropteru  strongylina  Rudolphi,  1819a,  p.  237.     Misprint  for 

Spiroptera. 

1828:  Spiroptera  strongyliformis  De  Blainville,  1828a,  p.  546. 
1866:  FUaria  strongylina  (Rudolphi)  Schneider,  1866a,  p.  101. 


/fomm. 


FIG.  1.— Arduenna  strongylina.    Median  view  of  cephalic  end.    b.  c.,  buccal  capsule;  cut.,  cuticle;  <«., 
esophagus;  lab.  p.,  labial  papillae;  ph.,  pharynx;  t.  b.  c.,  teeth  of  the  buccal  capsule.    X  560.    (Original.) 

SPECIFIC  DIAGNOSIS. — Cuticule  densely  striated  transversely,  increasing  in  thickness 
toward  the  anterior  extremity,  which  is  furnished  with  two  cervical  papillae  placed 
asymmetrically,  the  left  being  about  190  p  and  the  right  390  fi  from  the  anterior  ex- 
tremity. Beginning  at  a  point  280  fi  from  the  anterior  end  on  the  left  side,  a  narrow 
cuticular  wing  gradually  increasing  to  a  maximum  breadth  of  35  p.  extends  to  a  point 
about  2  mm.  from  the  posterior  extremity.  Mouth  44  to  45  ft  in  diameter  with  two 
lateral  lips  each  with  three  lobee,  having  a  small  round  papilla  at  the  base  of  each  of 
the  lobes.  Just  below  the  lips  and  projecting  into  the  mouth  cavity  are  two  chitinous 
teeth,  formed  by  a  prolongation  of,  the  wall  <?f.  the  pharynx  (fig.  1).  The  pharynx,  29  /* 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 


11 


wide  by  83  to  98  p  long,  is  marked  on  the  inside  by  a  series  of  chitinous  ridges  in  the 
form  of  continuous  spirals  (or  a  multiple  spiral),  all  running  in  the  same  direction  and 
appearing  like  the  threads  of  a  quadruple  screw. 

Esophagus  3.1  to  3.7  mm.  long,  or  about  one-fourth  of  the  body  length,  and  117  to 
127  ft  wide  at  its  widest  part  near  the  base.  Nerve  ring  0.35  mm.  and  excretory  pore 
0.48  mm.  from  the  anterior  end. 

Male  10  to  15  mm.  long,  averages  about  13  mm.  in  length;  301  to  387  p  wide  at  the 
widest  part  just  above  the  bursa.  The  bursal  wings  extend  from  a  point  about  1.2 
mm.  from  the  caudal  extremity  to  the  tip,  the  body  ending  in  a  blunt  point.  Bursal 
wings  irregularly  ovate,  ^^^^^^^.^ 

asymmetrical,  the  right  bur- 
sal  wing  being  about  twice 
as  wide  as  the  left  wing. 
The  bursa  contains  5  pairs 
of  stalked  papillae  asym- 
metrically arranged,  of 
which  4  pairs  are  preanal 
and  the  last  pair  is  post- 
anal.  Bursa  marked  with 
fine  longitudinal  striae,  in- 
creasing in  density  toward 
its  base  (fig.  2).  Spicules 
two,  grooved  on  the  ven- 
tral surface,  the  left  spicule 
2.24  to  2.95  mm.  long, 
very  slender,  ending  in  a 
fine  point  and  presenting 
a  slightly  concave  sur- 
face near  the  tip  on  the 
dorsal  side.  The  right 
spicule  (about  one-fifth  of 
the  length  of  the  left  spicule) 
is  stouter  and  blunter  at  the 
point,  measuring  10  [i  at  its  Jr  / 

base,  or  nearly  twice  the  jr  10fTim. 

width  of  the  base  of  the 
long  spicule,  and  is  457  to 
619  (i  long  (fig.  3).  Anus 
155  to  200  ft  from  the  pos- 
terior end  and  surrounded 
on  the  posterior  and  left  side 
by  a  cuticular  thickening 
(circumanal  ring),  the  outer 
edge  of  which  is  serrated. 

Female  16  to  22  mm.  long, 
263  to  420/i  wide;  average  maximum  width  368  p,  at  a  point  about  one-third  of  the 
distance  from  the  head  to  the  caudal  end.  For  the  next  third  of  the  distance  the 
width  remains  constant  except  for  a  slight  constriction  in  the  region  of  the  vulva. 
Beginning  at  a  point  about  two-thirds  of  the  distance  from  the  head  to  the  caudal 
end,  where  one  of  the  uteri  turns  back  on  itself,  the  width  gradually  diminishes  and 
then  abruptly  decreases  a  short  distance  in  front  of  the  anus.  Anus  215  to  275  p 
from  the  caudal  tip  (fig.  4). 

The  orbicular  naked  vulva  opening  near  the  left  side  close  to  the  lateral  cuticular 
wing  is  slightly  anterior  of  the  middle  of  the  body,  dividing  the  worm  anteriorly  and 
posteriorly  in  the  ratio  5 : 6.  Vagina  uniform,  about  49  p  in  diameter,  1.7  mm.  long, 


FIG.  2.— Arducnna  strongylina.  Bursa  of  male,  ventral  view,  cl., 
cloaca;  l.b.w.,  left  bursal  wing;  I.  sp.,  long  spicule;  po.  p.,  post- 
anal  papillae;  pr.  p.,  preanal  papillae;  r.  b.  w.,  right  bursal  wing; 
«.  sp.,  short  spicule;  v.  r.  c.,  ventral  ridge  of  the  cuticle.  X75. 
(Original.) 


12 


THE  ROUNDWORMS   OF   DOMESTIC   SWINE. 


extending  in  a  generally  posterior  direction,  joining  the  uteri  at  a  point  about  1.1  mm. 
from  the  vulva  measured  in  a  straight  line  (fig.  5;. 

Eggs  oval,  34  to  39 /i  long  by  20  ft  wide,  with  thick  shells.  Embryos  well  developed 
in  the  shell  before  oviposition  (fig.  6). 

HOSTS. — Domestic  hog  (Sus  scrofa  domestica),  wild  boar  (Sus  scrofafera). 

LOCATION. — Stomach  and  small  intestine. 

LOCALITIES  COLLECTED.— United  States:  Bethesda,  Md.;  Benning,  D.  C.;  Chicago, 
111.;  South  Omaha,  Nebr.;  St.  Louis,  Mo.;  Kansas  City,  Mo.;  Denver,  Colo.;  Brazoa 


Lsa —  :_=. 


Homm. 

FIG.  3.—  Arduenna  strongylina.  Posterior  end  of 
body  of  male,  viewed  from  right  side.  I.  sp. ,  long 
spicule;  s.  sp.,  short  spicule.  X  65.  (Original.) 

County,  Tex.  Europe:  Germany, 
France,  Hungary,  Roumania,  Italy. 
Asia:  Turkestan,  Indo-China. 

The  number  of  spiral  ridges 
in  the  pharynx  seems  to  vary 
both  with  the  sex  and  among 
different  individuals  of  the  same 
sex.  In  the  specimen  figured,  a 


Ho  mm. 


FIG.  4.— Arduenna  strongylina.  Posterior  end  of 
body  of  female,  viewed  from  left  side.  a. ,  anus; 
ov.,  ovary;  p.  ut.,  posterior  uterus;  red.,  rectum; 
ter.  p.,  terminal  papilla.  X  150.  (Original.) 


female  (fig.  1),  there  are  four  separate  ridges,  the  usual  number  for 
females.  Males  have,  as  a  rule,  but  three  spirals.  Kailliet  and  Henry 
(191  Ib)  mention  2  to  3  spiral  ridges  for  males  and  4  to  5  for  females. 
The  retractor  muscles  controlling  the  movements  of  the  right 
spicule  are  a  pair  of  narrow  lamellar  strips,  longitudinally  finely 
striated,  asymmetrically  twisted  in  the  center,  attached  at  the  pos- 
terior end  to  the  spicule  and  at  the  anterior  end  to  the  ventral  side 


THE   ROUNDWORMS  OF   DOMESTIC   SWINE. 


13 


//7/1 


of  the  body.     The  muscles  are  fullv  as  long  as  the  spicule  they  control 
(fig.  7). 

The  vas  deferens  appears  as  a  tube  of  darker  color  than  the  intes- 
tine, about  130  fjL  in  its  average  diameter,  and  extending  throughout 
the  posterior  third  of  the  body  length.  About  450  p  from  its  ter- 
minus it  rapidly  diminishes  in  diameter  toward  the  cloaca,  and  in 
the  specimen  figured  (fig.  8)  is  bent  in 
the  shape  of  the  letter  S.  The  seminal 
tube  is  very  long  and  convoluted,  re- 
sembling in  appearance  the  ovaries  of 
the  female.  Near  the  posterior  end  of 
the  male  the  intestine,  123  //  wide,  first 
crosses  above  the  vas  deferens  toward 
the  dorsum,  then  curves  underneath  as 
it  approaches  the  cloaca.  Its  terminus 
was  obscured  by  the  organs  lying  above 
it.  In  the  specimen  figured  (fig.  8)  the 
sheath  of  the  right  spicule  is  much  con- 
tracted and  appears  as  a  dark-colored 
bag  too  short  to  contain  the  entire 
spicule  and  within  which  the  base  of 

the  spicule 

may     be 

dimly 

seen.    The 

ventral 

surface   of 

the   male 

-in  the  re- 
gion im- 
mediately 

anterior  of 

the    bursa 

is    f  u  r  - 

nished  with  7  to  8  parallel  longitudinal 

, ,  cuticular    ridges     divided    transversely 

IQjuL.  into   serrations.     This  structure,  modi- 

FIQ.  6,—Arduenna  strongylina.  Lateral  fications    of  which   are   seen   in   many 

view  of  egg  removed  from  a  ruptured    nematodes.        including        PTimOCephdluS 
uterus,    o.    c.,   albuminous   covering;  .  . 

emb.,  embryo;  sh.,  sheii.  x  1,450.  sexalatiLS,  probably  assists  in  maintain- 
ing the  position  of  the  male  in  copula- 
tion, as  suggested  by  Ciurea  (1911).  The  anus  is  partially  encircled 
by  a  rim  of  thickened  cuticle,  the  outer  edge  of  which  is  ornamented 
with  serrated  cuticular  projections.  This  cuticular  thickening 
extends  along  the  posterior  and  left  sides  of  the  anus,  forming  about 


6. 


FIG.  5. — Arduenna  strongylina.  Ventral 
view  of  middle  of  body  of  female,  a.  tit., 
anterior  uterus;  int.,  intestine;  j.  ut., 
junction  of  the  uteri;  I.  c.  w.',  lateral 
cuticular  wing;  p.  ut.,  posterior  uterus; 
v.  vulva;  va.,  vagina.  X  58.  (Original.) 


14 


THE   ROUNDWORMS  OF   DOMESTIC   SWINE. 


two-thirds  of  a  complete  circle.     The  thickened  cuticle  seems  to 

project  downward  into  the  body  (fig.  2). 

Ciurea  (1911)   depicts  10  tactile  papillae  located  on  the  ventral 

surface  of  the  body  of  the  male,  close  to  the  tip  of  the  tail.     These 

could  not  be  seen  in  the  specimens  studied 
by  the  writer.  The  rectum  (fig.  4)  of  the 
female  is  about  80  /z  in  maximum  width  and 
nearly  as  long  as  the  distance  from  the  anus 
to  the  tip  of  the  tail.  In  the  region  immedi- 
ately posterior  of  the  anus  several  fine  lines 


FIG.  7. — Ar due nna  strongylina. 
Short  spicule  with  retractor 
muscles  viewed  from  right  side. 
ret.  m.,  retractor  muscles;  *.  sp., 
short  spicule.  X  80.  (Original.) 

can  be  seen  beneath  the 
cuticle,  converging  toward 
the  base  of  the  anus.  These 
are  probably  muscle  fibers 
controlling  the  rectum,  and 
are  seen  in  the  females  of 
many  nematodes.  A  pair 
of  papillae  close  to  the  tip 
of  the  tail  extend  laterally 
to  the  edges  of  the  caudal 
cuticle  on  the  ventral 
side. 

In  a  cross  section  of  Ar- 
duenna  strongylina  (fig.  9  of 
the  present  article) ,  Ciurea 
(1911)  shows  that  the  in- 
terior of  the  lateral  wing 
is  filled  with  a  substance 
shaped  like  the  letter  V 
when  viewed  in  this  posi- 
tion. In  its  reaction  to 
hematoxylin  it  resembles  the  thickened  wall  of  the  pharynx. 

The  same  drawing  (fig.  9)  also  shows  that  the  vagina  first  passes 
between  the  cuticle  and  muscular  wall  as  it  crosses  the  body  to  ex- 
tend along  the  right  side.  In  several  of  the  specimens  examined  by 
him,  Ciurea  (1911)  noticed  a  drop  of  hardened  cement  at  the  opening 


Ho  mm. 

FIG.  8.— Arduenna  stroru/yUna.  Posterior  end  of  body  of 
male,  viewed  from  left  side,  cl.,  cloaca;  int.,  intestine; 
I.  b.  w.,  left  bursal  wing;  po.  p.,  postanal  papillae;  pr.  p., 
preanal  papillae;  pr.  r. ,  perianal  ring;  sh.  I.  sp. ,  sheath  of  long 
spicule;  sh.  s.  sp.,  sheath  of  short  spicule;  ».  sp.,  short  spi- 
cule; v.  def.,  vas  deferens;  v.  r.  c.,  ventral  ridge  of  the  cuticle, 
X  58.  (Original.) 


THE   ROUNDWORMS  OP   DOMESTIC   SWINE. 


15 


FIG.  9. — Arduenna  ttrongylina.  Cross  section 
through  body  of  female  in  the  region  of  the 
vulva.  bd.  w.,  body  wall;  cut.,  cuticle;  «., 
eggs;  int.,  intestine;  tit.,  uterus;  v.,  vulva; 
va.,  vagina.  Enlarged.  ( After Ciurea,  1911. 
Text  fig.  1,  p.  131.) 


of  the  vulva,  and  in  cross  section  it  was  seen  that  the  same  material 

filled  the  terminus  of  the  vagina.     This  material  was  not  seen  in 

any  of  the  specimens  examined  by  the  present  writer.1 

The  vagina  (fig.  5)  extends  first  transversely  under  the  uteri  and 

intestine;  then  leading  above  these  organs  it  continues  posteriorly 

and  parallel  with  the  intestine  (except 

for  an  S-shaped  bend  near  its  middle) 

along  the  right  side  until  it  reaches 

the  junction  of  the  uteri. 

One  of  the  uteri,  commencing  at  the 

end  of  the  vagina,  extends  posteriorly 

and    dorsally  without    convolutions 

(except  for  an  S-shaped  bend  875  // 

from  its  vaginal  end)  until  it  reaches 

a  point  3.6  mm.  from  its  union  with 

the  vagina. 
Here  it  makes 
an  abrupt 
turn,  runs 
back  anteri- 
orly and  ven- 
trally,  paral- 
lel with  its  dorsal  limb,  until  its  outline  is 
lost  to  view  beneath  the  mass  of  eggs  distend- 
ing both  uteri  and  filling  the  body  cavity 
from  the  end  of  the  esophagus  to  within  a 
short  distance  of  the  anus,  greatly  obscuring 
the  outlines  of  the  organs.  Throughout  its 
visible  length  this  uterus  is  of  nearly  uniform 
diameter,  about  95  fi.  The  distal  ends  of  the 
two  uteri  are  at  opposite  extremities  of  the 
worm;  the  uterus  that  first  extends  poste- 
riorly ends  anteriorly  at  a  point  613  fi  anterior 
of  the  base  of  the  esophagus  in  a  long  con- 
voluted ovary  crowded  into  the  narrow  space 
between  the  esophagus  and  the  lateral  mus- 
cular wall.  The  other  uterus,  running  in  a 
similar  but  reverse  direction  from  the  uterus 

just  described,  turns  first  anteriorly  for  about  3.5  mm.,  then  posteriorly, 

ending  at  a  point  about  875  fj.  from  the  tip  of  the  tail.     The  diameter 

of  the  posterior  uterus,  like  that  of  the  anterior  uterus,  is  nearly 

i  Such  a  secretion  is  not,  however,  uncommon  among  nematodes.  The  writer  has  collected  many  speci- 
mens of  (Esophagostomum  columbianum  the  vulva  of  which  was  closed  by  a  plug  of  dark-red  secretion 
Insoluble  in  alcohol  but  which  could  easily  be  removed  by  a  needle.  Specimens  of  this  parasite  have  been 
observed  so  firmly  welded  in  copulation  that  hot  alcohol  did  not  cause  their  separation  and  they  yielded 
only  to  forcible  traction  with  a  needle  or  forceps. 


FIG.  10. — Arduenna  strongylina. 
General  view  of  body  of  male 
from  right  side,  b.,  bursa.  X  7. 
(Original.) 


16 


THE   ROUNDWORMS   OF   DOMESTIC   SWINfi. 


uniform,  about  95  fi.  The  posterior  ovary,  much  convoluted,  fills 
most  of  the  space  between  the  anus  and  the  terminus  of  the  posterior 
uterus  (fig.  4).  The  ovaries  are  long  filiform  tubes,  34  /j.  in  diameter 
in  their  narrowest  part.  The  thick-shelled  eggs  are  covered  with  a 
thin  irregular  membrane  resembling  the  albuminous  membrane  of  an 
ascarid  egg.  Under  high  power  a  faint  line  at  either  pole  can  be 
seen  running  transversely  through  the  thickness  of  the  shell,  sug- 
gesting an  operculum.  The  embryo  is  surrounded  by  a  thin  envel- 
ope, differentiated  from  the  shell  by  its  greater  translucence  and 
lack  of  granulation  (fig.  6).  Most  of  the  eggs  in  the  uterus  contain 
well-developed  embryos,  but  a  few  near  the  ovaries  appear  in  the 

morula  stage.  The  shell,  including 
the  translucent  membrane  surround- 
ing the  embryo,  is  4  //  thick,  the 
embryo  occupying  a  space  11  //  by 
24//. 

The  general  appearance  of  the  two 
sexes  is  represented  in  figures  10 
and  11. 

The  first  specimens  of  Arduenna 
strongylina  were  collected  by  Bremser 
and  figured  by  him  in  his  Icones 
Helminthum  (Bremser  1824c).  They 
were  first  described,  however,  by 
Rudolphi  (1819a,  p.  237).  His  de- 
scription may  be  freely  translated  as 
follows.: 

Head  slender,  continuous,  mouth  orbicular, 
body  somewhat  attenuated  anteriorly,  tail  of 
male  coiled  either  in  a  single  spiral  or  in  a 
spiral  and  a  half.  A  broad  wing  extending 
on  either  side  of  the  tail.  Spicule  very  long. 
Apex  of  the  tail  very  short,  naked.  Apex  of 
the  tail  of  the  female  depressed,  straight, 
subacute. 

In  a  preliminary  note  Rudolphi  (1819a)  gives  the  measurement  of 
the  males  as  about  5  lines  long  (=10.6  mm.)  and  the  females  as  7 
lines  long  (  =  14.9  mm.). 

Gurlt  (183 la)  is  the  first  on  record  to  collect  the  worm  from  domes- 
tic swine.  His  description  of  the  anatomy  of  Spiroptera  strongylina 
follows  Rudolphi's,  but  contains  also  the  statement  that  the  vulva 
is  situated  a  short  distance  in  front  of  the  anus.  He  describes  the 
mouth  as  smooth,  without  papillae.  Subsequently  (Gurlt,  1847a)  he 
added  to  his  description  a  note  on  the  anatomy  of  the  pharynx,  the 
first  reference  to  this  structure,  which  he  describes  as  banded  by  two 
spiral  muscles  (a  misinterpretation  of  the  spiral  chitinous  ridges  of 


FIG.  11  .—A  rduenna  strongylina.  General  view 
of  body  of  female  from  left  side,  a.,  anus; 
ut.,  uterus;  v.,  location  of  vulva.  X  7.5. 
(Original.) 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 


17 


.— Arduenna  strongy- 

Cephalic  end.    m., 

mouth;  ph.,  pharynx. 
Enlarged.  (After   ourit, 

1847a,  PI.  I,  fig.  8.) 


the  pharynx)  running  the  length  of  the  esophagus  in  opposite  direc- 
tions (fig.  12). 

Molin  (1860b)  describes  the  vulva  as  situated  posteriorly,  and 
gives  the  following  measurements:  Males,  11  to  15  mm;  females,  15 
to  23  mm,  which  figures  agree  closely  with  the  writer's  measurements 
of  Arduenna  strongylina. 

Schneider  (1866a)  reexamining  Rudolphi's  ma- 
terial, gives   a  correct  drawing  of  the  bursa  of 
Arduenna  strongylina,  showing  5  pairs  of  papillae,        / 
of  which  one  pair  is  postanal,  and  describes  the  / 
anus  as   surrounded  posteriorly  by  a  crown  of 
serrated   cuticular  prominences    (fig.   13).     His 
description,  however,  does  not  in  all  respects 
agree  with  his  drawing,  as  he  states  that  there 
are  6  pairs  of  papillae  while  the  drawing  shows 
only  5  pairs.     His  description  is  also  in  error  in 
regard  to  the  position  of  the  vulva,  which  he  TlG-  ] 
describes  as  directly  in  front  of  the  anus. 

Von  Linstow  (1879b)  states  that  the  two 
spicules  measure  respectively  0.72  and  0.26  mm. 
and  that  the  mouth  is  surrounded  with  6  round  papillae  curved  for- 
ward (fig.  14).  His  drawing  shows  the  pharynx  with  a  series  of 
parallel  ridges  instead  of  a  spiral.  A  comparison  of  his  drawing  (fig. 
14)  with  the  anterior  end  of  PJiysocephalus  sexalatus  (fig.  15)  gives 
rise  to  the  suspicion  that  Von  Linstow  has  mistaken  this  species  for 
Arduenna  strongylina,  an  opinion  first  expressed  by  Railliet  and 

Henry  (1911b). 

Zuern  (1882 a)  is  the  first  to  men- 
tion the  narrow  lateral  wing,  extend- 
ing longitudinally  along  one  side  of 
the  body.  He  describes  it,  however, 
as  being  in  a  median  position.  As 
has  been  shown,  it  extends  along  the 
left  side  only. 

Stossich  (1897b)  states  that  the  long 
spicule  is  three  times  the  length  of  the 
short  spicule,  a  ratio  evidently  derived 
from  Von  Linstow's  (1879b)  meas- 
urements. 

At  a  meeting  of  the  Helminthological  Society  of  Washington,  the 

writer  (Foster,  1911)  presented  a  note  on  Spiroptera  strongylina  in 

which  he  pointed  out  the  differences  between  the  anatomical  features 

of  specimens  tentatively  identified  by  him  as  Spiroptera  strongylina 

52865°— Bull.  158—12 3 


FIG.  13. — Arduenna  strongylina.  Bursa  of 
male,  ventral  view,  cl.,  cloaca;  po.  p., 
postanal  papillae;  pr.  p.,  preanal  papillae; 
pr.  r.,  perianal  ring.  Enlarged.  (After 
Schneider,  1866a,  p.  101.) 


18 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE. 


FIG.  14. — PhysocephaliM  sezalatus.  Lateral  view  of 
cephalicend.  lab.  p., labial  papillae;  ph.,  pharynx. 
Enlarged.  (After  Von  Linstow,  1879b,  Pl.V,  fig.  11.) 


and  the  descriptions  of  this  species  by  European  observers.  As  no 
European  specimens  were  at  hand  with  which  to  compare  the  speci- 
mens collected  in  this  country,  it  was  concluded  either  that  the 

American  form  represented  a 
distinct  species  or  else  the  de- 
scriptions of  European  writers 
were  in  error  in  some  important 
details.  In  order  to  determine 
which  of  the  two  alternatives 
was  correct,  specimens  collected 
in  the  United  States  were  for- 
warded to  Prof,  von  Linstow  for 
comparison  with  specimens  col- 
lected in  Europe,  and  other 
European  helminthologists  were 
asked  for  specimens  of  Spirop- 
tera  slrongylina.  The  specimens  sent  to  Von  Linstow  were  considered 
by  him  to  be  a  different  species  from  Spiroptera  strongylina.  There 
is,  however,  no  question  that  certain  European  specimens  recently 
received  from  Prof.  Gedoelst,  of  Brussels,  are  specifically  identical 
with  the  American 
form,  nor  can  it  be 
doubted  that  the  form 
taken  by  Railliet  and 
Henry  (191  Ib)  as 
Spiroptera  strongylina 
is  the  same  as  the 
American  form. 

In  regard  to  the 
length  of  the  spicules 
of  Arduenna  strongy- 
lina, the  writer's  ob- 
servations are  not  in 
accord  with  those  of 
Ciurea  (1911).  Meas- 
urements of  the  spic- 
ules of  over  35  males 
made  with  the  aid  of  a 
camera  lucida  and 
stage  micrometer 
show  that  the  long 
spicule  varies  between2.24  and2.95  mm.  in  length,  while  the  short  spic- 
ule  is  between  457  and  619  //  in  length.  The  corresponding  measure- 
ments given  by  Ciurea  are,  long  spicule,  977  //;  short  spicule,  221  /t. 
The  measurements  given  by  Railliet  and  Henry  (191  Ib)  are,  long 


iomm. 


FIG.  15. — PhysocepTialus  sexalatus.   Lateral  view  of  cephalic  end.   cut., 
cuticle;  lab.  p.,  labial  papillae;  ph.,  pharynx.     X  415.    (Original.) 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE.  19 

spicule,  2.75  to  2.9  mm.;  short  spicule,  500  to  570  /z,  thus  confirming 
the  present  writer's  observations. 

Arduenna  strongylina,  considered  a  rare  parasite  by  Dujardin 
(1845a),  Neumann  (1892a),  and  Railliet  (1893a),  is  now  known  to 
have  a  wide  range.  In  this  country  at  least  it  is  very  common,  as 
will  be  shown  later.  In  Europe  it  has  been  collected  from  the  wild 
boar  by  Bremser  (Rudolphi,  1819a)  in  Germany,  and  is  reported  by 
Dujardin  (1845a)  in  Austria,  and  by  Railliet  and  Henry  (191  Ib)  in 
prance  from  the  same  host.  It  has  been  reported  for  domestic  swine 
'in  Germany  (Gurlt,  183 la),  Hungary  (Von  Ratz,  1899d),  Italy 
(Piana,  1897e),  and  Roumania  (Ciurea,  1911).  Most  helmintholo- 
gists,  following  the  older  writers,  state  that  the  parasite  is  rare  and 
occurs  somewhat  more  commonly  in  the  wild  boar  than  in  domestic 
swine.  Dujardin  (1845a)  states  that  "out  of  19  wild  boars  dissected 
at  the  museum  of  Vienna,  only  2  had  this  worm  in  the  stomach."  In 
Roumania,  Ciurea  found  it  in  9  out  of  72  healthy  swine,  between  1 
and  27  specimens  being  found  in  a  single  host.  Outside  of  Europe  it 
has  been  reported  by  Von  Linstow  (1886c)  from  Turkestan,  and  by 
Railliet  and  Henry  (191  Ib)  from  Annam  Province,  Indo-China. 
Some  doubt,  however,  may  be  expressed  regarding  the  identity  of  the 
parasite  reported  by  Von  Linstow  (1886c)  since,  as  has  been  shown, 
Von  Linstow  (1879b)  has  apparently  confused  PJiysocepTialus  sexalatus 
with  Arduenna  strongylina.  The  references  to  this  parasite  in  the 
United  States  will  be  considered  in  detail  in  another  part  of  the  paper. 
Judging  from  its  abundance  in  the  United  States,  it  seems  not 
improbable  that  a  careful  examination  of  hogs'  stomachs  in  European 
slaughterhouses  would  show,  a  more  widespread  infection  than 
hitherto  reported.  The  specimens  received  by  this  bureau  from 
Gedoelst  were  unaccompanied  with  any  data  giving  the  host  or 
locality.  Doubtless  many  veterinary  schools  and  colleges  throughout 
Europe  contain  specimens  both  of  this  parasite  and  of  PTiysocephalus 
sexalatus  which,  like  the  specimens  received  from  Gedoelst,  have 
never  been  reported  in  the  literature. 

An  examination  of  the  literature  reveals  only  two  authentic  hosts 
for  Arduenna  strongylina,  namely,  the  European  wild  boar  and 
domestic  swine,  although  most  writers  subsequent  to  Diesing  (1851a) 
have  included  the  peccary  in  their  lists  of  hosts. 

Diesing  (185 la)  identified  as  Spiroptera  strongylina  some  specimens 
of  worms  in  the  Vienna  museum  collected  by  Natterer  in  Brazil, 
April  24,  1826,  from  the  stomach  of  the  white-lipped  peccary  (Dico- 
tyles  labiatus)  and  labeled  Spiroptera  suis  lalnati.  As  a  result  of  his 
identification  he  (Diesing,  1851a)  added  Dicotyles  albirostris  (  =  Dico- 
tyles  Idbiatus  Cuv.)1  to  the  previously  known  hosts  of  Spiroptera 

>  Dr.  H.  W.  Henshaw,  Chief  of  the  Bureau  of  Biological  Survey  of  the  United  States  Department  of 
Agriculture,  in  reply  to  a  letter  regarding  the  synonymy  of  Dicotyles  labiatus,  states  (Feb.  24,  1911)  that, 
according  to  Dr.  J.  A.  Allen,  of  his  bureau,  Dicotyles  labiatus  and  albirostris  are  synonyms,  labiatus  having 
preference  as  being  the  older  term,  the  correct  name,  however,  being  Tayassu  pecari  Fischer. 


20 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 


FIG.  16.— Arduenna  dentata.  Median  view 
of  cephalic  end.  ph.,  pharynx;  t.  b.  c., 
teeth  of  the  buccal  capsule.  Enlarged. 
(After  Von  Linstow,  1904f,  PI.  I,  flg.  5.) 


strongylina.  The  specimens  were  subsequently  studied  by  Molin 
(1860b),  recognized  as  a  new  species,  and  named  by  him  Spiroptera 
sexalata.  Later  helminthologists,  although  accepting  Molin's  species, 
have  continued  to  include  Dicotyles  Idbiatus  among  the  hosts  reported 
for  Arduenna  strongylina,  apparently  ignoring  the  fact  that  Molin's 
(1860b)  correction  of  Diesing's  (1851a)  identification  eliminates  the 

peccary  as  a  host  of  Arduenna  stron- 
gylina, since  this,  species  has  never 
been  reported  in  the  peccary  except  by 
Diesing  (1851a).  Stossich  (1897b)  ap- 
parently considered  Dicotyles  albiro- 
stris  and  D.  labiatus  as  separate  species, 
listing  under  the  former  Spiroptera  stron- 
gylina and  under  the  latter  the  para- 
sites collected  by  Nattererfrom  the  pec- 
cary and  described  by  Molin  (1860b). 
The  stomach  appears  to  be  the 
normal  location  for  Arduenna  strongylina;  Von  Ratz  (1899d),  how- 
ever, reports  its  occurrence  in  the  small  intestine. 

Arduenna  dentata  (Von  Linstow,  1904)  Railliet  and  Henry,  1911. 
Von  Linstow's  (1904f)  description  of  this  species  is  as  follows: 

Cuticula  finely  annulated.    The  mouth  leads  into  a  pharynx  0.11  mm.  long.    Ite 
entrance  is  armed  with  a  dorsal  and  a  ventral  tooth;  the  mouth  is  a  transverse  slit,  the 
border  of  which  shows  both  an- 
teriorly   and    posteriorly,    three 
notches   with    papillae   (fig.    16). 

1  ~  X./    I  "\.  \ 

The  esophagus  measures -g-g  of  the     \- 

entire  length  and  presents  a  spiral 
musculature.  In  a  young  worm 
14.6  mm.  long,  the  nerve  ring 
surrounds  the  esophagus  2.64  mm. 
from  the  head  end,  and  the  excre- 
tory pore  opens  at  a  point  situated 
0.31  mm.  behind  it.  The  male 
(25  mm.  long  by  0.79  mm.  broad) 
has  a  closely  involuted  tail  which 
resembles  that  of  Spiroptera 
strongylina.  The  spicules  are  re- 
spectively 0.35  and  0.92  mm.  long, 
the  shorter  one  bearing  at  its  end 
a  barb.  Immediately  anterior  of 
the  anus  on  each  side  there  are  four  preanal  papillae  situated  close  together;  behind 
it  there  is  one  papilla.  All  have  long  stalks.  The  anus  is  surrounded  by  a  broad 
ring,  notched  externally;  the  bursa  shows  longitudinal  rows  of  oval  scales.  (Fig.  17). 
The  female  grows  to  a  length  of  55  mm.  with  a  width  of  1.10  mm.  The  short  conical 
tail  is  curved  over  the  back;  the  vulva  is  placed  far  behind  the  middle  and  divides  the 
body  in  the  ratio  of  70  to  23.  The  eggs  are  small,  thick  shelled,  and  cylindrical,  meas- 
uring 0.039  by  0.017  mm. 


FIG.  17.— Arduenna  dentata.  Bursa  of  male,  ventral  view. 
d.,  cloaca;  I.  b.  w.,  left  bursal  wing;  I.  sp.,  long  spicule; 
po.  p.,  postanal  papillse;  pr.  p.,  preanal  papillae;  pr.  r., 
perianal  ring.  Enlarged.  (After  Von  Linstow,  1904f,  PL 
I,  fig.  7.) 


THE   KOUNDWORMS   OF   DOMESTIC    SWIXE.  21 

The  specimens  described  by  Von  Linstow  were  from  the  stomach 
of  Sus  cristatus  at  Chilaw,  Ceylon,  and  are  deposited  in  the  museum 
of  Colombo.  Railliet  and  Henry  (191  Ib)  identify  with  Von  Linstow's 
(1904f)  Spiropteradentata  certain  parasites  collected  from  the  stomachs 
of  pigs  slaughtered  at  Hue",  Annam  Province,  Indo-China,  and  include 
them  in  the  genus  Arduenna.  The  specimens  examined  by  Railliet 
and  Henry  (191  Ib)  differ,  however,  from  Von  Linstow's  (1904f)  de- 
scription in  the  position  of  the  vulva  and  the  length  of  the  spicules. 
According  to  the  former  authorities,  the  position  of  the  vulva  is  diffi- 
cult to  observe,  but  the  spicules  measure  3.75  to  4.23  mm.,  and  540  to 
650  fj.,  respectively. 

The  principal  differences  between  Arduenna  dentata  and  Arduenna 
strongylina  are  the  greater  size  of  the  former  and  the  fact  that  the 
chitinous  ring  surrounding  the  cloacal  opening,  described  for  Arduenna 
strongylina,  forms  an  almost  complete  circle  in  the  case  of  Arduenna 
dentata,  while  in  Arduenna  strongylina  it  includes  only  the  posterior 
and  left  sides.  Railliet  and  Henry's  measurements  for  Arduenna 
dentata  are:  Males:  25  to  35  mm.  long  by  700  to  800 //broad;  females: 
40  to  55  mm.  long  by  1.1  to  1.2  mm.  broad. 

Genus  PHYSOCEPHALUS  Diesing,  1861. 

• 

GENERIC  DIAGNOSIS. — Filariidse:  Body  elongated,  subcylindrical,  slightly  tapering 
anteriorly.  Head  marked  off  from  the  rest  of  the  body  by  a  cuticular  inflation  ending 
abruptly  in  a  circular  line  a  short  distance  anterior  of  the  posterior  end  of  the  pharynx. 
Extending  from  the  base  of  the  cuticular  inflation  to  about  the  middle  of  the  body 
are  6  lateral  cuticular  wings,  3  on  each  side,  the  middle  wing  of  each  3  being  broader 
than  the  other  two.  Mouth  with  2  trilobed  lips,  with  a  rounded  papilla  on  each  lobe, 
and  leading  into  an  inconspicuous  buccal  capsule  without  teeth.  Pharynx  relatively 
long  and  broad,  marked  by  prominent  ridges  forming  both  spirals  and  simple  rings, 
and  extending  the  length  of  the  pharynx  on  the  inside.  Tail  of  the  male  twisted 
spirally,  furnished  with  a  narrow  symmetrical  bursa  supported  by  four  pairs  of  preanal 
papillae.  Spicules  long  and  unequal,  the  left  spicule  about  five  times  the  length  of 
the  right  spicule.  Vulva  somewhat  posterior  of  the  middle  of  the  body;  eggs  smooth, 
with  thick  shells,  containing  well-developed  embryos  at  the  moment  of  oviposition. 
Endoparasitic  in  the  stomach  of  suidae. 

TYPE  SPECIES. — Physocephalus  sexalatus  (Molin,  1860)  Diesing,  1861. 

Physocephalus  sexalatus  (Molin,  1860)  Diesing,  1861. 

1860:  Spiroptera  sexalata  Molin,  1860b,  p.  957. 

1860:  Spiroptera    strongylina    suis    labiati:  Molin,    1860b,    p.    957 

(Museum  label). 
1861:  Pfiysocepfialus  sexalatus  (Molin)  Diesing,  1861  a,  p.  686. 

SPECIFIC  DIAGNOSIS. — Physocephalus:  Head  about  60  ji  in  diameter  at  the  anterior 
end,  furnished  with  2  tiilobed  lips,  each  lobe  being  ornamented  with  a  thick,  rounded 
chitinous  papilla  (fig.  15).  The  cuticle  of  the  head,  extending  from  the  mouth  to  a 
point  232  p  from  the  anterior  end,  ia  more  or  less  inflated.  Pharynx  cylindrical,  263 


22 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE. 


to  315  p  long  by  53  p  wide,  furnished  with  a  spiral  band  which  usually  breaks  up  into 
separate  rings  in  the  middle  of  its  course  and  resumes  the  spiral  toward  the  posterior 
end.  The  number  of  turns  to  the  spiral  varies  between  21  and  25.  There  is  a  cervical 
papilla  on  the  left  side,  281  ft  from  the  anterior  end.  The  excretory  pore  opens  on  the 
right  side,  526  p  from  the  anterior  end.  The  lateral  cuticular  wings,  3  on  each  side, 
commencing  at  the  base  of  the  cephalic  cuticular  inflation,  extend  posteriorly  for  a 
distance  about  one-third  of  the  body  length.  The  middle  wing  of  each  three  is  00  p 

wide  at  its  middle,  the  point  of 
greatest  width.  The  other  wings 
are  about  half  as  wide  (fig.  18). 

Male,  6  to  9  mm.  long,  measured 
in  a  straight  line.  Body  nearly 
uniform  in  diameter,  averaging 
263  ft,  and  attaining  ite  greatest 
width  of  315  p  at  the  point  of  the 
greatest  width  of  the  lateral 
wings.  The  narrow  bursal  mem- 
branes, about  half  the  width  of 
the  body,  extend  from  a  point 
about  1.4  or  1.5  mm.  from  the 
caudal  extremity,  to  and  includ- 
ing the  bluntly  pointed  tip  (fig. 
19).  Caudal  extremity  twisted 
into  a  fairly  regular  spiral,  having 
usually  three  turns.  Long  spicule 
grooved  on  the  ventral  side,  2.1 
to  2.25  mm.  in  length,  or  five  to 
six  times  the  length  of  the  short 
spicule,  very  slender,  gradually 
tapering  to  a  fine  needle  point. 
Short  spicule  300  to  350  p  long, 
relatively  broad  at  its  base,  sud- 
denly tapering  to  a  fine  point. 
The  ventral  surface  of  the  short 
spicule  is  provided  with  a  narrow 
wing  extending  nearly  to  the  tip. 
Bursa  furnished  with  eight  pairs 
of  papillae  (fig.  20).  Of  these  the 
four  pairs  of  preanal  papillae  are 
long  and  stalked;  the  postanal 
papillae,  close  to  the  tip  of  the  tail, 
are  very  small,  with  short  stalks. 
Female  13  to  19  mm.  long, 
average  about  16  or  17  mm.  Maximum  width  333  to  450  p  in  the  region  directly 
anterior  of  the  anus.  The  body  rapidly  increases  in  diameter  from  the  anterior 
end  to  the  region  of  greatest  width  of  the  lateral  cuticular  wings.  At  this  point 
the  diameter  is  nearly  as  great  as  in  the  region  of  the  anus.  It  then  rapidly 
diminishes  to  half  as  much  at  the  end  of  the  first  third  of  the  body;  then  slowly 
increasing,  it  reaches  a  maximum  near  the  anus  and  abruptly  diminishes,  the 
body  ending  in  a  blunt  point  furnished  with  a  mucronate  tip.  Anus  120  p  from  the 
caudal  end,  50  p  in  diameter  (fig.  21).  Vulva  posterior  of  the  middle,  35  p  in  diam- 
eter, dividing  the  body  in  the  ratio  of  9  to  8.  The  vagina  extends  posteriorly  (fig.  22). 
Uterus  bilobed,  the  ovaries  lying  at  opposite  extremities.  Eggs  34  by  15  ft,  slightly 
flattened  at  the  poles.  Embryo  well  developed  before  oviposition  (fig.  23). 


lo.mm. 

FIG.  18. — Physocephalus  sexalatus.  Dorsal  view  of  anterior 
end  of  body.  c.  cut.  inf.,  cephalic  cuticular  inflation;  c.  p., 
cervical  papilla;  ««.,  esophagus;  ex.  p.,  excretory  pore;  lab.  p., 
labial  papillae;  I.  c.  to.,  lateral  cuticular  wings;  n.  r.,  nerve 
ring;  ph.,  pharynx.  X  150.  (Original.) 


THE   ROUNDWORMS  OF   DOMESTIC   SWINE. 


23 


HOSTS. — White-lipped  peccary  (Tayassu  pecan),  wild  boar  (Sus  scrofa  fera), 
domestic  hog  (Sus  scrofa  domestica). 

LOCATION. — Stomach  and  small  intestine. 

LOCALITIES  COLLECTED. — Brazil;  Italy;  Germany;  Roumania;  Madagascar;  Indo- 
China;  United  States,  east,  middle,  and  southwest.  (Apparently  same  range  as 
Arduenna  strongylina.) 

As  already  mentioned,  Physoceph- 
alus  sexalatus  was  first  identified 
as  Spiroptera  strongylina  by  Diesing 
(185  la).  Molin  (1860b)  subse- 
quently described  the  specimens 
under  the  name  Spiroptera  sexalata, 
and  the  following  year  Diesing 
(186 la)  placed  the  species  in  a  new 
genus  Physocephalus,  of  which  it  is 
the  type  and  only  species.  The 
specimens  studied  both  by  Molin 
and  Diesing  were  collected  by  Nat- 
terer  from  the  white-lipped  peccary 
in  Brazil,  April  24,  1826,  and  depos- 
ited in  the  Vienna  Museum  labeled 
Spiroptera  strongylina  suis  labiati. 

Molin's  (1860b)  somewhat  meager 
description  sums  up  the  salient 
points  (the  lateral  wings  and  spiral 
tail  of  the  male)  by  which  Phy- 
socephalus sexalatus  may  be  recog- 
nized. He  describes  the  males  as 
7  mm.  long  and  2  mm.  wide,  and 
the  females  as  9  to  13  mm.  long  and 
3  to  5  mm.  wide.  The  mouth  is  de- 
scribed as  bilobed,  each  lobe  with  a 
three-cornered  margin.  Diesing 
(1861a),  although  creating  a  new 
genus  from  Molin's  species,  adds 
little  to  our  knowledge  of  its  anat- 
omy. 

It  has  already  been  noted  that 
Von  Linstow  (1879b)  has  appar- 
ently mistaken  Physocephalus  sexa- 
latus for  Arduenna  strongylina. 
His  measurements  of  the  spicules 
(0.72  mm.  for  the  long  and  0.26  mm.  for  the  short  spicule)  are,  how- 
ever, much  too  short  for  A.  strongylina  and  also  for  P.  sexalatus. 

Von  Drasche  (1884a),  in  his  reexamination  of  Diesing's  and  Molin's 
specimens,  made  a  careful  study  of  the  bursal  papillae  and  the  struc- 


Momm. 


c/. 


FIG.  19.— Physocephalus  sexalatus.  Posterior  end 
of  body  of  male.  6.  w.,  bursal  wing;  cl.,  cloaca; 
1.  *p.,long  spicule;  pr.  p.,  preanal  papillae;  ». 
sp.,  short  spicule;  v.  r.  c.,  ventral  ridge  of  the 
cuticle.  X  50.  (Original.) 


24 


THE   ROUNDWORMS   OP   DOMESTIC   SWIXE. 


ture  of  the  lateral  wings,  illustrating  the  description  with  drawings, 
which  were  of  great  value  to  the  present  writer  in  verifying  his  iden- 
tification. In  common  with  Railliet  and  Henry  (191  Ib)  the  present 
writer  was  unable  to  find  the  pair  of  papillae  depicted  by  Von  Drasche 
(1884a,  fig.  24  of  this  article)  close  to  the  edge  of  the  anus.  Ciurea 
(1912),  however,  depicts  a  pair  of  papillae  immediately  posterior  of 
the  anus,  which  he  states  are  not  easily  seen.  At  the  extreme  tip  of 
the  tail  Von  Drasche  (fig.  24)  shows  three  pairs  of  minute  apparently 
sessile  papillae.  In  reality  there  are  four  pairs  of  minute  stalked 
papillae  at  this  point.  These  appeared  very  clearly  with  a  high 


^lo  mm, 

FIG.  20.—Physocephalus  sexalatus.  Bursa  of  male,  viewed  from  left  side,  cl.,  cloaca;  I.  b.  w.,  left  bnrsal 
wing;  1.  sp.,  long  spicule;  po.  p.,  postanal  papillae;  pr.  p.,  preanal  papillae;  r.  6.  w.,  right  bnrsal  wing; 
sft.  s.sp.,  sheath  of  short  spicule;  s.sp.,  short  spicule;  v.  w.,  ventral  wing  of  short  spicule.  X  100.  (Orig- 
inal.) 

power  in  mounts  presenting  a  somewhat  lateral  view  (fig.  20).  The 
structure  at  the  tip  of  the  tail  with  its  rows  of  minute  papillae  is  not 
unlike  that  depicted  by  Ciurea  (1911)  for  the  bursa  of  Arduenna 
strongylina.  As  already  stated,  however,  no  such  structure  was  seen 
by  the  present  writer  on  the  bursa  of  this  species.  In  a  cross  section 
of  P.  sexalatus  (fig.  25)  Von  Drasche  shows  that  the  projecting  cuticle 
forming  the  lateral  wings  has  corresponding  depressions  inward. 

Stossich's  (1897b)  description  of  P.  sexalatus  follows  that  of  Molin 
and  Von  Drasche.  Piana  (1897e),  in  an  article  on  Simondsia  para- 
doxa,  mentions  finding  two  other  species  of  nematodes  in  the  same 
bottle  containing  the  specimens  of  Simondsia.  He  identified  these 
as  being  Spiroptera  strongylina  and  PhysocepJialus  sexalatus.  These 
.specimens  were  from  an  Italian  pig. 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE. 


25 


Railliet  and  Henry's  (191  Ib)  description  of  Physocephalus  sexa- 
latus  is  based  on  specimens  collected  from  a  hog  slaughtered  at  Hue", 
Indo-China.  These  authors  also  report  having  observed  it  in  material 
from  Madagascar  in  1905. 

Ciurea  (1912)  reported  Spiroptera  sexalata  in  domestic  swine 
slaughtered  at  Piatra  Neamtz,  Roumania,  in  1910.  Five  out  of  72 
healthy  swine  were  infested  with  from  one  to  thirty  of  these  para- 


FIG.  21. — Physocephalus  sexalatus.  Posterior 
end  of  body  of  female,  ventral  view.  a. ,  anus; 
a.  ut.,  anterior  uterus;  int.,  intestine;  /.  a.  ut., 
loop  of  anterior  uterus;  ov.,  ovary;  p.  ut.,  pos- 
terior uterus.  X  50.  (Original.) 


Jfomm. 


FIG.  22.— Physocephalus  sexalatus.  Ventral  view  of  body  of  fe- 
male in  the  region  of  the  vulva,  int.,  intestine;  ut.,  uterus; 
v.,  vulva;  va.,  vagina.  X  95.  (Original.) 


sites  in  the  stomach.  In  three  cases  they  were  found  associated 
with  Arduenna  strongylina,  and  once  with  Gnafhostoma  hispidum. 
In  this  latter  case  the  parasites  were  found  in  the  ulcer  caused  by 
G.  Tiispidum.  The  worms  were  partially  or  entirely  buried  in  the 
mucosa,  but  no  lesions  were  attributed  to  them.  Ciurea's  (1912) 
.description  and  drawings  of  Physocephalus  sexalatus  agree  in  most 
respects  with  the  present  writer's  observations,  the  few  differences 
being  noted  in  the  course  of  this  article. 


26 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE. 


Seurat  (1912)  reports  finding  several  hundred  specimens  of  Spi- 
roptera  sexalata  partially  buried  in  the  mucosa  of  the  stomach  of  an 

ass  slaughtered  in  Algeria  during  July,  1911. 
A  subsequent  examination  of  the  fourth 
stomachs  of  six  dromedaries  revealed  numer- 
ous specimens  of  this  species  hidden  between 
the  folds  of  the  mucosa,  associated  with 
Hsemonchus  contortus.  While  the  description 
of  the  specimens  agrees  in  general  with  the 
present  writer's  observations,  the  measure- 
ments are  all  somewhat  larger.  The  width 
of  the  middle  lateral  wing  (110  to  120  /£  as 
given  by  Seurat)  is  over  twice  as  great  as 
that  given  by  the  present  writer,  while  the 
vulva  is  described  as  located  at  the  anterior 
third  of  the  body,  instead  of  slightly  posterior 
of  the  middle,  as  described  by  Railliet  and 
Henry  (191  Ib),  Ciurea  (1912),  and  Foster 
(1912)  (the  present  article). 

Seurat  (1912)  also  found  in  the  dromedary 
another  form  which  he  considers  as  a  variety 
and  designates  as  var.  cristata.  This  form 
is  distinguished  from  the  typical  species  by 
having  four  longitudinal  crests  on  the  head, 
formed  by  four  cuticular  folds,  and  having  four  cuticular  spines  in 
the  mouth  cavity.  In  this  variety  the  position  of  the  vulva  is  not 
constant,  but  varies  from  the  posterior 
third  of  the  body  to  an  anterior  position. 
As  Seurat's  (1912)  measurements  of 
Physocephalus  sexalatus  differ  considerably 
from  the  present  writer's,  and  as  the  species 
has  hitherto  been  reported  only  in  the 
Suidse,  it  would  seem  desirable  to  reserve 
an  opinion  until  his  statements  can  be 
confirmed. 

The  stomach  is  the  normal  location  for 
Physocephalus  sexalatus.  Von  Linstow 
(1879b)  reports  Filaria  strongylina  as  col- 
lected from  the  small  intestine  of  a  hog 
by  Dr.  V.  Bering,  of  Stuttgart.  As  has 
been  shown,  Von  Linstow  apparently  con- 
fused Physocephalus  sexalatus  with  Ardu- 
enna  strongylina;  it  would  seem  there- 
fore, that  P.  sexalatus  may  occasionally  occur  in  the  small  intestine. 
In  most  specimens  examined  by  the  author  the  cuticle  of  the  head 
appears  as  shown  in  fig.  18,  which  is  closely  similar  to  the  form 


FIG.  23.— Physocephalus  sexalatus. 
Lateral  view  of  egg  removed 
from  a  ruptured  uterus,  a.  c., 
albuminous  covering;  emb., 
embryo;  sh.,  shell.  X  1,450. 
(Original.) 


FIG.  24.— Physocephalus  sexalatvt. 
Bursa  of  male,  ventral  view.  ad.  p. , 
adanal  papillae;  I.  b.  w.,  left  bursal 
wing;  Z.sp.,longspicule;  po.  p., post- 
anal  papillae;  pr.  p.,  preanal  papillae; 
r.  b.  w.,  right  bursal  wing;  s.sp.,  short 
spicule.  X280.  (After  Von  Drasche, 
1884a,  Pl.XTV,flg.3.) 


THE   ROUNDWORMS   OF   DOMESTIC    SWIXE. 


27 


FIG.  25. — Physocephalussexalattu.  Cross 
section  through  anterior  part  of  body. 
bd.  w.,  body  wall;  I.  c.  w.,  lateral  cu- 
ticular  wings.  X  280.  (After  Von 
Drasche,  1884a,  PL  XIV,  fig.  4.) 


depicted  by  Von  Drasche  (1884a).  In  about  20  per  cent  of  the 
specimens  examined,  however,  the  cuticle,  from  the  lips  to  the 
beginning  of  the  lateral  cuticular  wings, 
is  inflated  into  two  hemispherical  vesicu- 
lar wings  (fig.  26).  This  second  form  is 
not  mentioned  by  Molin  (1860b)  or  Von 
Drasche  (1884a),  but  possibly  may  be 
referred  to  byDiesing  (186 la)  in  the  ex- 
pression "epidermide  in  bullam  inflata 
tunicatum"  in  his  description  of  the 
genus  PJiysocephalus. 

The  pharynx  of  P.  sexalatus  is  about 
three  tunes  as  long  and  twice  as  broad  as 
that  of  Arduenna  strongylina,  and  this, 
together  with  the  lateral  wings  character- 
istic of  the  genus,  are  the  salient  points  in 
distinguishing  the  females  of  the  two  genera.  At  first  sight  the 
ridges  of  the  pharynx  appear  to  form  separate  rings  and  are  so 

described  by  Von  Linstow 
(1879b  and  in  liti) .  By  careful 
focusing,  however,  it  is  seen 
that  these  ridges  form  a  simple 
spiral  at  the  anterior  end  of  the 
pharynx  and  after  making  four 
or  five  turns  split  up  into  sepa- 
rate rings.  At  the  posterior 
end  of  the  pharynx  they  are 
again  joined  into  a  simple  spiral 
(fig.  18) .  The  final  loop  of  the 
anterior  spiral  forms  the  first 
ring  of  the  series,  and  the  begin- 
ning of  the  posterior  spiral  takes 
its  origin  from  the  lower  part  of 
the  last  ring.  The  number  of 
loops  to  the  spirals  and  the  num- 
ber of  sep  arate  rings  is  sub j  ect  to 
considerable  variation.  A  rather 
extreme  case  is  seen  in  fig.  27. 
Here  the  first  spiral  has  five 
loops  followed  by  a  detached 
ring.  This  in  turn  is  followed 
by  a  spiral  of  four  loops,  after 
which  are  two  detached  rings. 
The  final  spiral  consists  of  11 
continuous  loops.  In  every  case,  however,  so  far  as  observed,  the  ridges 
form  both  spirals  and  rings,  commencing  and  ending  with  a  spiral,  and 


FIG.  26.— Physocephalus sexalatus.  Ventral  view  of  body 
offemale.  a., anus;  c.cut. inf., cervical cutieular infla- 
tion; 1.  c.  w.,  lateral  cuticular  wings;  p.,  vulva.  X  7. 
(Original.) 


28 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE. 


not  a  series  of  parallel  bands,  as  described  by  Von  Linstow  (1879b) ,  or  a 

continuous  spiral,  as  described  by  Von  Drasche  (1884a),  Railliet  and 

Henry  (191  Ib),  and  Ciurea  (1912). 

Railliet  and  Henry  (191  Ib)  mention  two  asymmetrical  cervical 

papillaB,  the  right  papilla  being  220  /*  and  the  left  420  JM  from  the 

anterior  end.  As  seen  by  the  present 
writer  the  left  papilla  has  a  broad 
base  and  a  blunt  point  and  pene- 
trates the  cuticle  281  /i  from  the  an- 
terior end,  or  a  little  anterior  of  the 
base  of  the  cephalic  inflation.  The 
right  papilla  was  not  seen  by  the 
present  writer,  but  on  the  right  side, 
not  far  from  the  location  of  the  papilla 
as  given  by  Railliet  and  Henry 
(191  Ib),  the  excretory  canal  opens. 
The  end  of  the  canal  is  a  slender 
tube  penetrating  the  middle  lateral 
wing  and  looking  not  unlike  a  long 
stalked  papilla  (fig.  18).  Its  true 
nature  has  been  shown  by  Ciurea 
(1912),  who  made  a  cross  section  of 
the.  worm  at  this  point.  The  lateral 
situation  of  the  excretory  pore  is  ap- 
parently unique  among  nematodes, 
the  usual  situation  being  ventral. 

The  lateral  cuticular  wings  unite 
just  posterior  of  the  base  of  the  ce- 
phalic inflation  (fig.  18).  Here  the 
cuticle  forms  an  inverted  pocket  like 
the  handle  of  a  table  drawer  (fig.  27). 
The  lateral  cuticular  wings  are  densely 
striated  at  the  base,  giving  them  a 
puckered  appearance.  Although  the 
cuticle  of  the  entire  body  is  striated, 
these  striations  appear  more  promi- 


ey 


wings;  n.  r.,  nerve  ring;   ph.,  pharynx. 
X  150.    (Original.) 


lomm 

FIG.  27. — Physocephalus  sexalatus.  Lateral 
view  of  anterior  end  of  body.  c.  cut.  inf., 
cervical  cuticular  inflation;  cut.,  cuticle; 
es.,  esophagus;  ex.  p.,  excretory  pore;  lab.  -,  , . 

P.,  labial  papiii®;  i.  c. «.,  lateral  cuticular  nently  on  the  lateral  wings,  particu- 
larly at  their  base,  than  elsewhere. 
The  esophagus,  about  four-fifths  of 
the  length  of  the  lateral  wings,  is  densely  striated  transversely, 
with  a  very  narrow  lumen;  nerve  ring  439  //  from  the  anterior  end 
(fig.  18).  The  intestine  is  more  or  less  convoluted  throughout  its 
course,  especially  posteriorly. 

The  male  (fig.  28)  is  about  half  the  length  of  the  female,  but  as  2 
to  3  mm.  of  the  posterior  end  is  twisted  into  a  spiral,  its  apparent 
length  is  much  shortened. 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 


29 


The  spiral  of  the  caudal  end  of  the  male  appeared  in  a  few  cases  as 
a  single  coil  like  that  of  Arduenna  strongylina.  In  other  cases  it  con- 
sisted of  an  irregular  double  twist  (fig.  28).  In  the  greater  number 
of  specimens  examined,  however,  it  formed  a  broad  open  spiral  like 
a  corkscrew  (fig.  19).  Comparing  the  spiral  to  the  thread  of  a  screw, 
and  considering  the  tip  of  the  tail  as  the  point  of  the  screw,  the  spiral 
resembles  a  left-handed  screw  with  three  (rarely  four)  threads;  no 
cases  were  seen  in  which  the  spiral 
revolved  in  the  opposite  direction. 

The  bursal  wings  are  described 
as  symmetrical  by  Railliet  and 
Henry  (191  Ib)  and  are  so  depicted 
by  Von  Drasche  (1884a).  The  right 
wing  is,  however,  a  little  longer  than 
the  left  wing  (fig.  19).  Ciurea  (1912) 
considers  that  it  is  also  narrower, 
but  this  statement  could  not  be  veri- 
fied by  the  present  writer.  Ciurea 
(1912)  states  that  the  bursal  wings 
extend  throughout  the  twisted  por- 
tion of  the  tail.  As  seen  by  the 
present  writer  they  extend  only  about 
half  this  distance  (fig.  19).  The 
cuticle  on  the  ventral  side  of  the 
male  (fig.  19),  commencing  at  some 
distance  anterior  of  the  spiral,  is 
marked  with  longitudinal  striations 
intercepted  by  transverse  lines,  ap- 
pearing under  high  power  as  longi- 
tudinal folds  of  the  cuticle  separated 
by  transverse  ridges.  A  similar  struc- 
ture has  already  been  noted  on  the 
ventral  surface  of  Arduenna  strongy- 
lina (fig.  2) .  As  in  most  nematodes, 
the  papillae  are  arranged  symmetri- 
cally on  either  side  of  the  median 
line.  Their  grouping  and  structure 
have  already  been  discussed. 

The  intestine  is  much  convoluted,  growing  broader  close  to  the 
cloaca.  The  vesicula  seminalis  occupies  most  of  the  body  cavity  in 
the  posterior  end,  maintaining  a  fairly  uniform  diameter  until  it 
disappears  dorsal  of  the  intestine  which  conceals  the  ductus  ejacu- 
latorius.  The  long  convoluted  testis  which  extends  to  the  middle  of 
the  body  presents  no  specific  characteristic  features.  The  anus  is 


I- 


mm. 


FIG.  28.— Physocephalus  sexalatus.  General 
view  of  body  of  male.  5. ,  bursa;  es. ,  esoph- 
agus; *p*.,spicules.  X  23.  (Original.) 


30  THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 

circular,  like  that  of  Arduenna  strongylina,  but  not  surrounded  by  a 
serrated  ring. 

I  The  vulva  (35  ft  in  diameter),  as  in  Arduenna  strongylina,  appar- 
ently occupies  a  somewhat  lateral  rather  than  ventral  position,  open- 
ing toward  the  right  side  (fig.  22).  It  is  situated  just  below  the 
middle  of  the  body,  dividing  the  worm  in  the  ratio  of  9  to  8.  Accord- 
ing to  Ciurea  (1912)  the  cuticle  in  the  region  of  the  vulva  is  marked 
with  longitudinal  thickenings  which  may  interlock  with  the  cuticular 
ridges  on  the  ventral  surface  of  the  male,  and  thus  assist  in  maintain- 
ing the  position  of  the  male  in  copulation.  The  vagina,  extending 
posteriorly  along  the  right  side,  is  at  first  50  ft  in  diameter,  but  gradu- 
ally broadens  to  105  ft  at  its  posterior  end,  where  it  disappears  from 
the  ventral  side,  extending  dorsal  of  a  lobe  of  the  uterus.  The  dis- 
tance from  the  vulva  to  this  point  is  976  /*.  The  wall  of  the  vagina 
is  relatively  thick,  composed  of  transverse  muscle  fibers.  The  lumen 
is  20  //  in  diameter.  Eggs  containing  well-developed  embryos 
ready  to  pass  out  could  be  seen  in  single  file  in  the  lumen  of  the 
vagina  near  the  opening  (fig.  22).  Railliet  and  Henry  (191  Ib) 
describe  the  vulva  as  opening  posteriorly  at  the  limit  of  the  third 
and  four  fifths  of  the  body.  Von  Linstow  (in  litt)  places  it  somewhat 
posterior  of  the  middle  of  the  body,  dividing  the  worm  in  the  ratio 
of  10  to  9. 

The  arrangement  of  the  uteri  and  ovaries  in  the  body  of  the  female 
is,  so  far  as  could  be  seen,  similar  to  that  of  Arduenna  strongylina. 
The  convoluted  ovary  of  the  posterior  uterus  occupies  the  caudal 
extremity  of  the  worm,  its  terminus  disappearing  dorsal  of  the  pos- 
terior uterus.  A  loop  of  the  anterior  uterus  extends  nearly  to  the 
caudal  end.  The  exact  length  of  the  vagina  was  not  determined. 
A  loop  of  the  posterior  uterus,  corresponding  to  the  loop  of  the  anterior 
uterus,  lies  underneath  the  anterior  uterus  and  extends  nearly  to  its 
terminus.  The  union  of  the  vagina  with  the  uteri  was  not  seen,  nor 
was  the  anterior  ovary  traced  throughout  its  length.  While  neither 
uterus  was  followed  throughout  its  entire  length,  the  two  termini, 
one  posterior  the  other  anterior,  the  posterior  uterine  loop,  and  the 
anterior  loop,  are  all  similar  to  the  arrangement  seen  more  clearly  in 
Arduenna  strongylina. 

Ciurea  (1912)  depicts  a  pluglike  protuberance  at  one  of  the  poles 
of  the  eggs  of  Physocephalus  sexalatus,  which  bears  a  superficial  re- 
semblance to  the  operculum  of  a  Trichuris  egg,  but  does  not  penetrate 
the  eggshell  as  in  the  latter  case.  This  feature  was  not  seen  by  the 
present  writer;  however,  a  faint  transverse  line  could  be  seen  at 
either  pole  (fig.  23),  which  apparently  is  the  line  of  fissure  along  which 
the  shell  breaks  when  the  embryo  is  liberated. 


THE   EOUNDWORMS   OF   DOMESTIC   SWINE.  31 

COMPARISON    OF    PHYSOCEPHALUS    SEXALATUS    AND    ARDUENNA 

STRONGYLINA. 

The  following  comparison  of  appearances  of  Arduenna  strongylina 
and  Physocephalus  sexalatus  will  assist  in  separating  the  two  species 
without  the  aid  of  a  magnifier. 

Males. — Tail  of  Physocephalus  sexalatus  ending  in  a  spiral,  Ardu- 
enna strongylina  ending  in  a  single  coil;  PJiysocephalus  sexalatus 
shorter  and  slenderer  than  Arduenna  strongylina. 

Females. — PJiysocephalus  sexalatus  straight,  or  nearly  so;  speci- 
mens preserved  in  alcohol  when  lifted  out  of  a  petri  dish  with  a 
needle  bend  sharply  in  the  middle.  Body  slenderer  than  Arduenna 
strongylina,  except  toward  the  posterior  end,  which  is  thicker  and 
blunter. 

Alcohol  specimens  of  Arduenna  strongylina  are  usually  curved  in  a 
half  circle.  They  are  thicker  in  the  middle  of  the  body  than  Physo- 
cephalus  sexalatus  and  pointed  at  both  ends.  On  being  lifted  with  a 
needle  they  do  not  collapse  like  PJiysocephalus  sexalatus,  but  maintain 
their  crescentic  shape. 

As  has  already  been  stated,  Molin  (1860b)  was  the  first  to  distin- 
guish this  species  from  Arduenna  strongylina,  with  which  it  had  been 
confused  by  Diesing  (185 la).  Besides  the  specimens  from  the  white- 
lipped  peccary,  Molin  (1860b)  also  found  two  females  of  this  species 
in  a  bottle  containing  specimens  of  Arduenna  strongylina  collected 
by  Bremser  from  the  stomach  of  the  wild  boar  and  deposited  in  the 
Vienna  Museum.  That  it  has  only  twice  been  reported  in  Europe 
in  association  with  Arduenna  strongylina  is  perhaps  due  to  confusion 
of  the  two  species,  an  error  which  appears  to  have  occurred  in  at  least 
one  case  (Von  Linstow,  1879b).  In  the  United  States  it  has  been 
found  in  nearly  every  case  in  which  specimens  of  Arduenna  strongylina 
have  been  collected. 

OTHER  SPECIES  REFERRED  TO  PHYSOCEPHALUS  SEXALATUS. 

Two  other  worms  have  been  thought  by  different  writers  to  be  possi- 
bly identical  with  Physocephalus  sexalatus,  viz,  Simondsia  paradoxa 
(Cobbold,  1864b)  from  Sus  scrofa  domestica  and  Filaria  nitidulans 
(Schneider,  1866a)  from  Tapirus  americanus. 

Simondsia  paradoxa  was  collected  from  the  stomach  of  a  German 
hog  kept  at  Regent's  Park,  London,  and  was  described  by  Cobbold 
(1864b).  In  a  later  work  (1879b)  Cobbold  suggests  the  possibility 
of  the  worm  being  identical  with  Physocephalus  sexalatus.  The 
immensely  hypertrophied  uterus  of  Simondsia  paradoxa,  forming  a 
rosette  entirely  covering  the  caudal  end  of  the  female,  however,  clearly 
differentiates  this  species  from  Physocephalus  sexalatus. 


32  THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 

In  his  description  of  Physocephalus,  Von  Drasche  (1884a)  suggests 
the  possibility  that  Schneider's  (1866a)  Filaria  nitidulans  may  be 
identical  with  P.  sexalatus.  Both  worms  are  characterized  by  three 
lateral  wings  on  either  side,  and  the  caudal  extremity  of  the  males  of 
both  species  are  alike  in  the  number  and  arrangement  of  the  papillae. 
The  measurements  of  Filaria  nitidulans  (males  20  mm.,  females  32 
mm.)  are,  however,  far  in  excess  of  the  measurements  for  Physo- 
cephalus sexalatus,  and  the  position  of  the  vulva  of  Filaria  nitidulans 
is  stated  as  "directly  above  the  anus,"  while  the  vulva  of  Physo- 
cephalus sexalatus  is  slightly  posterior  of  the  middle  of  the  body. 
Ciurea  (1912),  who  has  recently  reexamined  Schneider's  material,  was 
unable  to  determine  the  location  of  the  vulva  of  F.  nitidulans.  He 
gives,  however,  a  summary  of  the  differences  between  Filaria  nitidu- 
lans and  Physocephalus  sexalatus,  proving  conclusively  that  they  be- 
long to  different  species,  although  he  considers  that  Filaria  nitidulans 
should  be  included  in  the  genus  Physocephalus.  Stossich  (1897b),  fol- 
lowing Von  Drasche's  (1884a)  suggestion,  considered  the  worms 
identical.  He  listed  Tapirus  americanus  as  a  host  of  Physocephalus 
sexalatus  and  combined  Molin's  (1860b)  measurements  of  P.  sexalatus 
with  Schneider's  (1866a)  measurements  of  Filaria.  nitidulans. 

DISTRIBUTION  OF  ARDUENNA  STRONGYLINA  AND  PHYSOCEPHA- 
LUS SEXALATUS  IN  THE  UNITED  STATES. 

Of  nine  lots  of  Arduenna  strongylina  collected  in  various  parts  of 
the  United  States  and  now  deposited  in  the  helminthological  collection 
of  the  Bureau  of  Animal  Industry,  only  two  have  been  found  not  to 
contain  examples  of  Physocephalus  sexalatus,  and  both  of  these  lots 
contain  only  a  few  specimens.  The  distribution  of  Arduenna  strongy- 
lina  is  therefore  similar  to  that  of  Physocephalus  sexalatus,  since  the 
latter  species,  according  to  the  writer's  experience,  is  practically  always 
associated  with  the  former. 

To  determine  the  distribution  of  these  parasites  and  the  frequency 
of  their  occurrence  in  the  United  States  the  literature  was  searched 
for  references  to  Spiroptera  strongylina.  Four  such  references  were 
found,  as  below;  in  most  cases  Physocephalus  sexalatus  was  probably 
also  present  but  not  recognized. 

1.  Curtice  (1892g),  in  a  list  of  parasites  infesting  domestic  animals 
and  man  in  the  United  States,  includes  the  following  entry :  "Spiroptera 
strongylina.  Hud.  Host,  Sus  scrofa  domestica.  Location,  stomach," 
followed  by  the  remark,  "Is  often  found  with  the  food  and  attached  to 
the  walls."  Specimens  No.  2058  of  the  helminthological  collection  of 
the  Bureau  of  Animal  Industry  were  collected  and  identified  by  Cur- 
tice as  Spiroptera  strongylina.  These  specimens  have  been  examined 
by  the  writer,  who  verified  Dr.  Curtice's  identification.  A  few  exam- 
ples of  Physocephalus  sexalatus  were  also  present. 


THE   ROUNDWORMS  OF   DOMESTIC   SWINE.  33 

2.  Stiles  and  Hassall  (1894e)  include  Spiroptera  strongylina  in  their 
preliminary  catalogue  of  the  parasites  in  the  collection  of  the  United 
States  Bureau  of  Animal  Industry.     They  report  the  parasite  as  com- 
mon.    The  specimens  referred  to  by  them  (No.  2057  of  the  bureau 
collection)  have  been  reexamined  by  the  writer,  and  many  specimens 
of  Physocephalus  sexalatus  were  found  with  the  specimens  of  Arduenna 
strongylina.     Stiles  and  Hassall's  specimens  were  collected  at  Ben- 
ning,  D.  C. 

3.  Francis  (1894a)  reported  Spiroptera  strongylina  in  a  list  of  para- 
sites collected  by  him  in  Brazos  County,  Tex.     It  is  reported  as  com- 
mon.    The  specific  name  is  followed  by  an  interrogation  point  in 
parenthesis  to  indicate  the  author's  doubt  as  to  the  correctness  of  the 
identification.     Considering  the  inaccuracy  of  the   descriptions  of 
Arduenna  strongylina,  then  available,  it  is  not  to  be  wondered  that 
Francis,  noticing  the  discrepancies  between  the  descriptions  and  the 
anatomical  features  seen  in  his  specimens,  should  question  the  identi- 
fication.    On  the  other  hand,  it  is  quite  possible  that  the  specimens 
collected  by  Francis  were  Physocephalus  sexalatus,  or  included  this 
species. 

4.  Kaupp  (1910)  reported  the  occurrence  of  Spiroptera  strongylina 
in  hogs  raised  in  the  Missouri  Valley.     His  article  is  illustrated  with 
original  drawings,  one  of  which  shows  the  caudal  end  of  the  female 
with  the  vulva  apparently  on  the  right  side,  a  little  anterior  of  the 
anus. 

For  the  sake  of  additional  data,  letters  were  sent  to  the  inspectors 
in  charge  at  some  of  the  principal  slaughterhouses  of  the  United 
States,  requesting  information  in  regard  to  the  occurrence  of  Spirop- 
tera strongylina  in  hogs.  Replies  were  received  from  South  Omaha, 
Chicago,  St.  Louis,  and  Kansas  City.  The  inspector  in  charge  at 
South  Omaha  reported  that  fully  80  per  cent  of  the  hogs  examined 
were  infested.  It  was  reported  from  St.  Louis  that  "the  worms 
occur  in  considerable  numbers  in  the  mucous  coating  of  the  stomach." 
The  parasite  is  reported  as  very  frequent  in  hogs  slaughtered  at 
Kansas  City;  out  of  1,450  hogs  examined,  1,052  were  infested.  In 
some  stomachs  as  many  as  140  worms  were  collected.  From  Chicago 
it  was  reported  that  1,000  hogs  had  recently  been  examined,  and  690 
were  found  infested.  The  worms  were  found  on  the  surface  of  the 
mucous  membrane  or  attached  by  the  head.  Several  hundred 
specimens  obtained  by  scraping  the  mucosa  from  the  stomachs  of  a 
number  of  infested  hogs  were  received  from  this  city.  These  worms 
were  found  to  be  Arduenna  strongylina  and  Physocephalus  sexalatus. 

Reports  from  slaughterhouses  regarding  the  occurrence*  of  parasites 
are  of  but  little  value  in  determining  the  localities  infested  by  a  given 
parasite,  as  the  animals  slaughtered  are  received  from  widely  scat- 
tered sections  of  the  country.  Enough  data  have  been  gathered, 


34  THE  ROUNDWORMS   OF   DOMESTIC   SWINE. 

however,  to  warrant  the  assertion  that  the  parasites  occur  throughout 
the  middle  and  southwestern  (and  probably  eastern)  United  States. 
Specimens  have  been  collected  by  Hall  in  1908  from  a  hog  kept  at 
Bethesda,  Md.,  in  all  probability  of  eastern  origin.  They  have  also 
been  collected  by  Kilborne  at  Washington,  D.  C.,  and  by  Stiles  and 
Hassall  at  Benning,  D.  C. ;  in  the  latter  case,  however,  it  is  possible 
that  the  host  animal  had  been  shipped  to  the  local  slaughterhouse 
from  a  Western  or  Central  State. 

RELATIVE   FREQUENCY   OF   THE   TWO    SPECIES. 

That  Physocephalus  sexalatus  occurs  less  abundantly  than  Arduenna 
strongylina  in  American  swine  is  indicated  by  the  following  data : 

All  the  worms  contained  in  a  bottle  of  specimens  forwarded  from 
Chicago  were  sorted  out  by  species  and  sex.  The  bottle  contained 
744  specimens.  Of  these,  599,  or  approximately  80  per  cent,  were 
Arduenna  strongylina,  and  the  remaining  145,  or  20  per  cent,  were 
Physocephalus  sexalatus.  Of  the  599  specimens  of  Arduenna  strongy- 
lina, 399,  or  56  per  cent,  were  females,  and  260,  or  44  per  cent,  were 
males.  A  smaller  percentage  of  males  was  found  among  the  speci- 
mens of  Physocephalus  sexalatus.  Of  the  145  specimens  found,  69 
per  cent  were  females  and  31  per  cent  were  males. 

LESIONS  ASSOCIATED  WITH  ARDUENNA  STRONGYLINA,  ARDUEN- 
NA DENTATA,  AND  PHYSOCEPHALUS  SEXALATUS. 

From  an  economic  standpoint  these  three  species  are^probably  of 
considerable  importance.  Prior  to  1899  it  was  not  considered  that 
Arduenna  strongylina  was  especially  injurious  to  swine.  Neumann 
(1892a),  in  mentioning  that  Spiroptera  strongylina  caused  small  sub- 
mucous  tumors  of  the  stomach  and  that  no  morbid  disturbances  were 
attributed  to  it,  summed  up  the  general  opinion  of  the  time  regarding 
the  economic  importance  of  the  parasite.  More  recent  reports, 
however,  indicate  that  these  parasites  should  be  regarded  as  the 
possible  etiology  of  serious  gastric  disorders. 

Von  Ratz  (1899d)  found  Spiroptera  strongylina  very  common 
among  swine  hi  Hungary,  and  attributed  to  this  parasite  several 
epizootics  of  a  rather  serious  nature,  in  one  of  which,  out  of  a  herd  of 
230  sows,  21  were  seriously  affected  and  6  died.  Some  of  the  symp- 
toms were  described  as  follows: 

The  diseased  sows  suffered  from  loss  of  appetite,  eating  very  little  and  in  the  worst 
cases  finally  refusing  all  food;  on  the  other  hand,  they  drank  water  excessively  and 
were  very  restless,  continually  pawing  the  ground. 

Describing  the  post-mortem  lesions  seen  in  the  stomach,  Von  Ratz 
says: 

At  the  pyloric  end  the  mucous  membrane  was  covered  with  a  thick,  lamellous, 
firmly  adhering  pseudomembrane,  which  upon  being  removed  revealed  a  superficial 
loss  of  tissue  of  the  mucous  membrane.  Under  the  mucous  membrane  lay  numerous 


THE   BOUNDWORMS  OF   DOMESTIC   SWINE.  35 

Spiroptera  strongylina  fastened  partly  in  the  stomach  wall,  partly  in  the  pseudo- 
membrane.  In  addition  to  these  lesions,  dark  red  spots  the  size  of  a  penny  were  to  be 
seen,  corresponding  to  which  were  numerous  openings  the  size  of  a  needle  prick, 
through  which  projected  the  bodies  of  the  nematodes. 

While  no  data  are  at  hand  regarding  the  effect  of  Arduenna  dentata 
on  its  host,  hi  view  of  its  close  similarity  with  Arduenna  strongylina 
and  the  fact  that  both  species  are  parasitic  in  the  stomach,  it  may  be 
assumed  that  the  former  species  is  as  injurious  as  the  latter. 

Railliet  and  Henry  (19 lib)  report  that  the  stomach  of  a  sow  from 
Madagascar  from  which  specimens  of  PJiysocephalus  were  collected, 
presented  a  very  intense  gastritis  with  a  quantity  of  small  elevations 
on  the  mucosa. 

The  information  and  material  supplied  by  the  inspectors  of  this 
bureau  have  shown  that  lesions  of  a  nature  similar  to  those  described 
by  Von  Ratz  are  frequently  associated  with  the  presence  of  Arduenna 
strongylina  in  this  country. 

The  inspector  in  charge  at  South  Omaha  reported  that  "Ten  per 
cent  of  the  affected  stomachs  show  a  highly  inflamed  zone  surround- 
ing the  infested  area,  and  hi  a  few  instances  considerable  ulceration 
exists."  The  inspector  in  charge  at  St.  Louis  was  of  the  opinion 
that  "they  produce  no  apparent  lesions."  The  inspector  in  charge 
at  Chicago  forwarded,  in  addition  to  the  loose  specimens  already 
mentioned,  several  pieces  of  hogs'  stomachs  showing  the  worms  in 
situ.  The  heaviest  infestations  were  found  hi  portions  from  the 
pyloric  end  of  the  stomach,  which  in  one  instance  presented  the 
folio  whig  appearances:  A  piece  of  stomach  from  the  pyloric  end 
about  21  cm.  wide  by  20  cm.  long  contained  a  cluster  of  worms  buried 
in  a  glairy  mucous  mass  of  yellowish  color  firmly  attached  to  the  normal 
mucous  membrane,  and  forming,  hi  the  opinion  of  pathologists  in  the 
Pathological  Division  of  this  bureau,  to  whom  the  tissues  were  referred, 
a  pseudomembrane  of  necrotic  tissue.  Several  such  worm  clusters 
were  observed  on  the  portion  examined,  the  worms  in  nearly  every 
case  being  buried  in  a  mass  of  mucus,  and  appearing  as  bright  red 
lines  in  the  yellowish  mass.  (See  PI.  I.)  In  places  the  necrotic 
tissue  had  apparently  sloughed  off,  leaving  deep,  red,  depressed  areas 
of  irregular  shape.  These  areas  varied  in  size  from  a  few  millimeters 
to  2  or  3  centimeters  in  diameter.  The  same  lesions  could  be  observed 
under  the  necrotic  tissue  when  this  had  been  removed  with  forceps. 
The  condition  was  described  by  one  of  the  pathologists  as  "undoubt 
edly  ulcerous." 

It  was  suggested  by  the  pathologists  who  examined  the  material 
that  the  pseudomembranes  might  have  been  caused  by  Bacillus 
necrophorus  gaining  an  entrance  to  the  submucosa  as  the  result  of  the 
piercing  of  the  mucous  membrane  by  the  parasitic  worms;  examina- 
tions of  scrapings  from  the  stomach  lesions  revealed  a  few  specimens 
of  the  bacillus.  As  explained  by  Mohler  and  Morse  (1904),  this 


36  THE  ROUNDWORMS   OF   DOMESTIC   SWINE. 

bacillus  is  normally  found  in  the  stomachs  of  hogs  and  other  animals, 
and  while  under  ordinary  circumstances  it  has  no  pathological  effect, 
if  enabled  through  some  lesion  to  the  mucous  membrane  to  gain 
access  to  impaired  tissue,  its  proliferation  results  in  the  sloughing  of 
the  mucous  membrane  and  the  formation  of  ulcers. 

Mohler  and  Morse  (1904),  describing  necrobacillosis  of  the  digest- 
ive tract,  state:  "The  necropsy  in  such  cases  revealed  hemorrhages 
and  erosions  in  the  stomach,  but  no  areas  of  coagulation, ' '  an  accurate 
description  of  the  conditions  found  by  the  present  writer.  The  char- 
acteristic odor  described  for  lesions  of  Bacillus  necrophorus  was  only 
faintly  present,  being  modified  perhaps  by  the  boric  acid  with  which 
the  specimen  was  sprinkled  and  which  may  account  for  the  paucity 
of  the  parasitic  flora  found. 

How  deeply  Arduenna  strongylina  is  capable  of  penetrating  into  the 
submucosa  was  well  shown  in  one  of  the  specimens  forwarded  from 
Chicago.  A  piece  of  the  cardiac  portion  of  the  stomach  contained 
a  worm  12  mm.  long  which  had  bored  diagonally  into  the  mucosa  to  a 
depth  of  10  mm.,  only  the  caudal  end  projecting  above  the  "surf  ace. 
The  hole  made  was  similar  to  a  pin  prick,  a  simile  used  by  Von  Ratz 
(1899d)  in  describing  the  lesions  observed  by  him.  Indeed  Von 
Ratz's  description  is  practically  identical  with  the  conditions  found 
by  the  present  writer. 

The  habit  of  boring  into  the  mucosa  characteristic  of  these  para- 
sites would  seem  an  ideal  method  of  inoculating  the  submucosa  of  the 
host  with  Bacillus  necrophorus  if  any  were  present,  and  this,  consid- 
ered in  connection  with  the  conditions  observed  in  infested  stomachs, 
indicates  that  the  worms  may  be  the  indirect  cause  of  grave  ulcera- 
tion.  Considered  apart  from  their  possible  r61e  as  infective  agents, 
the  mechanical  injury  to  the  stomach  walls  due  to  the  penetration  of 
the  worms  in  numbers  would  seem  to  be  a  serious  factor  even  if  the 
worms  were  unassociated  with  bacilli.  Moreover,  the  livid  red  color 
of  the  worms  in  situ  in  the  stomachs  examined  would  seem  to  indicate 
that  they  feed  on  blood,  an  additional  reason  for  regarding  them  as 
dangerous  parasites.  The  whole  question,  however,  of  the  patho- 
genicity  of  the  parasites,  and  as  to  their  relationship  to  the  lesions 
observed,  remains  open  for  further  investigation. 

An  examination  of  the  stomach  portions  received  showed  specimens 
of  Physocephalus  sexalatus  attached  in  the  same  manner  as  already 
noted  for  Arduenna  strongylina;  hence  the  former  parasite  may  be 
considered  only  less  dangerous  than  the  latter,  as  it  is  less  abundant. 

LIFE  HISTORY. 

Nothing  is  known  in  regard  to  the  development  of  the  worms  from 
the  egg  to  the  adult.  The  wide  distribution,  the  frequency  of  the 
parasites,  and  the  similarity  of  the  eggshell  to  that  of  an  ascarid, 


THE   ROUNDWOEMS   OF   DOMESTIC    SWINE.  37 

suggest  the  possibility  that  development  occurs  without  an  inter- 
mediate host.  From  the  fact  that  the  embryos  are  well  developed  in 
the  uterus  before  oviposition,  it  would  seem  that  but  little  time  is 
required  for  incubation,  and  the  thickness  of  the  shell  would  indicate 
the  necessity  of  the  gastric  juice  of  the  host  to  dissolve  the  shell  and 
liberate  the  embryo. 

PREVENTIVE  MEASURES. 

In  the  absence  of  knowledge  as  to  the  life  cycle  of  the  parasites,  no 
prophylaxis  or  treatment  specially  adapted  to  the  case  can  be  formu- 
lated. The  following  general  prophylactic  measures  are  suggested: 

1.  Hogs  suffering  from  loss  of  appetite  or  failing  to  fatten  under 
proper  food  and  hygiene  should  be  examined  for  evidence  of  infection 
by  killing  one  or  two  and  looking  in  the  stomach  for  worms;  or,  where 
practicable,  the  feces  of  the  entire  herd  may  be  examined  micro- 
scopically. 

2.  Those  swine  found  infested  with  stomach  worms  should  be 
isolated  from  noninfested  or  presumably  noninfested  swine  in  clean 
pens,  and  the  dung  removed  daily  and  mixed  with  quicklime  or 
disposed  of  by  carting  it  to  places  to  which  hogs  do  not  have  access. 

3.  The  noninfested  swine  should  not  be  allowed  to  remain  in  the 
same  pens  formerly  occupied  by  the  infested  animals,  but  should  have 
clean  quarters.     The  old  pens  should  be  thoroughly  disinfected  with 
lime  after  removing  the  dung  and  burning  over  the  ground  where 
feasible. 

MEDICINAL  TREATMENT. 

Youatt  (1847c),  referring  to  Spiroptera  strongylina,  recommends 
turpentine  and  salt  with  the  food  for  treating  these  worms.  Coal-tar 
creosote,  gasoline,  and  copper  sulphate  have  been  found  more  or  less 
efficacious  in  treating  stomach  worms  (Hsemonchus  contortus)  in  sheep, 
and  similar  treatment  might  be  tried  on  pigs  (see  Bureau  of  Animal 
Industry  Circular  102).  Santonin  and  calomel,  3  grains  each  per 
hundred  pounds  of  body  weight,  given  after  a  fast  of  12  to  16  hours, 
is  another  remedy  which  deserves  trial. 

Whatever  drug  is  used  should  first  be  given  in  small  quantities  and 
tried  on  a  few  of  the  most  heavily  infested  swine,  the  size  of  the  dose 
being  increased  as  occasion  demands. 


38  THE   ROUND  WORMS   OF  DOMESTIC   SWINE. 

KEY  TO  THE  ROUNDWORMS  PARASITIC  IN  DOMESTIC  SWINE. 

The  arrangement  of  the  following  key  to  the  roundworms  which 
have  been  reported  by  various  authors  as  parasites  of  hogs  is  purely 
artificial  and  arbitrary  and  indicates  nothing  as  to  the  systematic 
relationship  of  the  different  forms.  A  classified  list  of  the  round- 
worms  of  swine  is  given  later  on  page  41. 

Section. 

Parasitic  in  alimentary  tract 1 

Parasitic  in  respiratory  tract 16 

Parasitic  in  other  organs 17 

1.  Diameter  of  body  at  middle  over  3  mm 2 

Diameter  of  body  at  middle  less  than  3  mm 3 

2.  Anterior  extremity  furnished  with  a  protractile  prolwscis  covered  with  spines. 

Male  6  to  10  cm.  long,  3  to  5  mm.  in  diameter.  Female  20  to  35  cm.  long, 
4  to  9  mm.  in  diameter.  Eggs,  87  to  100  n  long,  subcylindrical,  smooth, 
with  3  envelopes.  In  small  intestine,  usually  attached  to  the  mucous 

membrane Gigantorhynchus  hirudinareus. 

Anterior  extremity  without  protractile  proboscis.  Mouth  with  3  prominent 
lips.  Male  15  to  17  cm.  long,  3  to  3.2  mm.  thick.  Female  20  to  25  cm. 
long,  5  to  5.5  mm.  thick.  Eggs  oval,  66  fi  long,  thick-shelled,  surface  cov- 
ered with  mammillate  projections.  In  small  intestine,  sometimes  in  biliary 
tract  and  pancreas Ascaris  suum. 

3.  Less  than  5  mm.  in  length 4 

Over  5  mm.  in  length 5 

4.  Vulva  anterior  of  middle  of  body.     Ovoviviparous.     Females  3  to  4  mm. 

long,  60  fi  in  diameter.  Males  1.4  to  1.6  mm.  long,  40  /z  in  diameter,  with 
a  short  finger-like  process  on  each  side  of  the  anal  opening.  Adults  in 

small  intestine,  larvae  encysted  in  skeletal  muscles Trichinella  spiralis. 

Vulva  posterior  of  middle  of  body.  Females  (parthenogenetic;  parasitic 
males  lacking)  3.75  mm.  long,  80  fi  in  diameter.  Eggs  45  fi  long  by  25  /t 
broad,  with  thin  shells.  In  small  intestine Slrongyloides  suis.1 

5.  Head  covered  with  spines;  separated  from  the  body  by  a  deep  constriction. 

Male  15  to  25  mm.  long.     Female  22  to  31  mm.  long.    Eggs  70  fi  long  by  39 

fi  wide.     In  stomach Gnathostoma  hispidum. 

Head  without  spiny  armature 6 

6.  Posterior  end  of  body  of  female  with  relatively  large  rosette-like  excrescence 

containing  the  hypertrophied  uterus.    Male  12  mm.  long.     Female  15  mm. 

long.     In  stomach     Simondsia  paradoxa.2 

Posterior  end  of  body  of  female  without  uterine  rosette 7 

7.  Anterior  portion  of  body  slender,  like  a  whiplash,  about  twice  as  long  as  the 

thicker  posterior  portion.  Male  with  single  spicule.  Male  33  to  40  mm. 
long.  Female  34  to  50  mm.  long.  Eggs  52  to  56  /*  long,  ellipsoidal,  with 
an  opening  at  each  pole  closed  by  a  plug-like  operculum,  and  brownish  in 

color.     In  cecum Trichuris  suis. 

Body  continuous,  not  flagelliform  anteriorly.    Male  with  two  spicules 8 

1  While  Strongyloides  papillosvs  («=  Trichosoma  papiUosum  Wedl.)a  parasite  of  sheep  has  frequently  been 
reported  for  the  pig,  this  is  probably  the  result  of  confusion  with  Strongyloidu  suis.  The  Stronyyloides  of 
the  pig  Is  somewhat  larger  than  the  form  found  in  sheep. 

*  Included  by  the  present  writer  among  the  Filariidse  on  account  of  the  inequality  of  the  spicules.  Its 
position  in  this  family  is  not,  however,  defin  tely  established.  See  footnote  on  page  9,  second  paragraph. 


THE   ROUNDWORMS   OF   DOMESTIC   SWINE.  39 

Section. 

8.  Male  with  two  equal  or  subequal  spicules;  tail  with  membranous  bursa  sup- 

ported by  paired  rays  and  eggs  with  thin  shells 9 

Male  with  two  spicules  of  very  unequal  length;  tail  with  lateral  longitudinal 
bursal  membranes  supported  by  stalked  pappillse.  Eggs  with  thin  or  thick 
shells 12 

9.  Mouth  enlarged  to  forma  buccal  capsule 10 

Mouth  small;  buccal  capsule  not  present.    Male  5  mm.  long.    Female  8  to  8.5 

mm.  long.  Spicules  130  /j.  long.  Vulva  about  2  mm.  from  the  tip  of  the 
tail.  Eggs,  45  fi  long  by  36  (JL  wide.  In  stomach "Strongylus"  rubidus.1 

10.  Buccal  capsule  broader  than  long,  mouth  bordered  by  a  crown  of  numerous, 

small,  pointed  processes.    Male  8  to  12  mm.  long.     Female  12  to  15  mm. 
long.     Spicules  slender,  1.13  mm.  long.     Vulva  a  short  distance  in  front  of 
anus,  piptuberant.    Adults  in  large  intestine,  larvae  encysted  in  the  wall 
of  the  large  and  small  intestines,  forming  nodules.  .(Eesophagostomum  dentatum. 
Buccal  capsule  spherical  or  elongated ,  border  of  mouth  smooth 12 

11.  Buccal  capsule  spherical.     Male  7  mm.  long,  0.2  mm.  thick.     Female  8  mm. 

long,  0.3  mm.  thick.     Vulva  prominent.     In  small  intestine. 

Globocephalus  longemucronatus. 

Buccal  capsule  elongated,  oval.  Male  4.4  mm.  long,  0.38mm.  thick.  Female 
6.5  mm.  long,  0.52  mm.  thick.  Spicules  590 /t  long.  Vulva  sunken.  In 
small  intestine Crassisoma  urosubulatum. 

12.  Anterior  end  of  body  supplied  with  numerous  cuticular  tubercles  or  shields. .     13 
Anterior  end  of  body  without  cuticular  tubercles 14 

13.  Male  30  to  50  mm.  long  by  about  250  /JL  thick.     Female  80  to  145  mm.  long, 

300  to  350  fjL  thick.  Left  spicule  16  to  17  mm.  long;  right  spicule  140  to  180  fj. 
long.  Vulva  4  to  5  mm.  from  tip  of  the  tail.  Eggs  55  to  60  ft  long  by  32  to 
36  [i  wide.  In  the  mucosa  of  the  esophagus  and  pharynx. 

Gongylonema  scutatum.2 

Male  14  to  50  mm.  long,  175  to  195  fj.  thick.  Female  37  to  40  mm.  long  (?  or 
longer),  350  n  thick.  Left  spicule  4  to  5  mm.  long,  right  spicule  84  to  110 
fj.  long.  Vulva  about  2  mm.  from  the  tip  of  the  tail.  Eggs  52  to  56  ,«  long 
by  32  fj.  wide.  In  the  mucosa  of  the  esophagus  and  pharynx. 

Gongylonema  pulchrum. 

14.  Body  furnished  anteriorly  with  six  longitudinal  lateral  wings,  three  on  each 

side,  the  middle  wing  of  each  three  wider  than  the  other  two.  Ridges  of 
pharynx  forming  a  simple  spiral,  breaking  up  into  separate  wings.  Male 
6  to  9  mm.  long.  Female  13  to  19  mm.  long.  Spicules  2.1  to  2.25  mm .  long, 
and  300  to  350  /t  long,  respectively.  Vulva  anterior  of  the  middle  of  the 
body.  Eggs  34  u.  long  by  15 ,«  wide,  with  rather  thick  shells.  In  stomach. 

Physocephalus  sexalatus. 

Anterior  portion  of  body  with  a  single  longitudinal  wing.  Ridges  of  pharynx 
forming  a  continuous  multiple  spiral 15 

1  "Strongylus"  rubidus  does  not  belong  in  the  genus  Strongylus.  Its  proper  position  is  in  the  family 
Trichostrongylinse.  As  yet,  however,  no  genus  has  been  established  to  which  it  may  be  assigned. 

*  Reported  by  Korzil  (1877a)  and  Piana  (1896b).  According  to  Neumann  (1894d),  however,  the  measure- 
ments given  by  Korzil  indicate  that  the  species  studied  by  him  is  Gongylonema  pulchrum,  Molin  1857. 
The  measurements  given  by  Piana(1896b)  are,  males  60  to  80  mm.  long  by  130  ft  broad;  females  80  to  145mm. 
long,  600  n  broad.  Except  that  G.  pulchrum  is  smaller  than  G.  scutatum,  there  is  but  little  morphological 
difference  between  the  two  species.  The  species  are  considered  identical  by  Railliet  (1893a),  although  this 
view  is  not  accepted  by  Neumann  (1894d)  and  others.  G.  scutatum  is  normally  a  parasite  of  ruminants. 


40  THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 

Section. 

15.  Male  10  to  15  mm.  long.  Female  16  to  22  mm.  long.  Long  spicule  2.24  U> 
2.95  mm.  in  length,  5  to  6  times  as  long  as  the  short  spicule.  Vulva  some- 
what anterior  of  the  middle  of  the  body.  Eggs  34  to  39  p  long  by  20  ft  wide, 

with  rather  thick  shells.     In  stomach Arduenna  strongylina. 

Male  25  to  35  mm.  long,  700  to  800  /j.  broad.     Female  40  to  55  mm.  long,  1.1  to 
1.2  mm.  broad.     Long  spicule  3.75  to  4.23  mm.  long.     Short  spicule  540  to 
650  ft  long.     Vulva  three-eighths  of  the  distance  from  the  anterior  end. 

Arduenna  dentala. 

16. l  Spicules  about  4  mm.  long,  each  terminated  by  a  single  hook.     Vagina  about 

2  mm.  long.  Male  between  12  and  25  mm.  in  length.  Female  between  20 
and  50  mm.  in  length.  Vulva  near  anus.  Eggs  between  57  and  100  /t  in 
length  and  39  and  73  ft.  in  width.  In  trachea  and  bronchi..  Atetastrongylus  apri. 
Spicules  1.5  mm.  long,  each  terminated  by  a  double  hook.  Vagina  about 
500  [i  Jong.  Male  between  12  and  25  mm.  in  length.  Female  between 
20  and  50  mm.  in  length.  Vulva  near  anus.  Eggs  between  57  and  100  fi 
in  length  and  39  and  72  fi  in  width.  In  trachea  and  bronchi. 

Mctastrongylus  bremvaginatus. 

17.2  Encysted  in  skeletal  muscles,  microscopic  in  size.     Cysts  slightly  elongated, 

ovoid,  long  axis  parallel  to  the  muscle  fibers,  about  400  fi  long  by  250  fi  broad. 

Trichinella  spiralis  (larvae). 

Free  in  peritoneal  cavity,  in  kidneys,  in  ureters,  in  the  bladder,  or  encysted 
in  fat  of  kidneys  or  loins 18 

18.  Male  under  40  mm.  long 19 

Male  over  12  cm.  long 20 

19.  Male  25  to  37  mm.  long.     Female  37  to  40  mm.  long.    Two  spicules,  equal  or 

subequal,  about  0.8  mm.  long.  Vulva  less  than  2  mm.  from  the  tip  of  the 
tail.  Eggs  100  fi  long  by  56  fi  wide,  with  thin 'shells.  In  kidneys,  ureters, 
and  encysted  in  fat  of  kidneys  and  loins Stephanurus  dentatus. 

20.  Male  14  to  40  cm.  long,  4  to  6  mm.  in  diameter.     Female  20  cm.  to  1  m.  long, 

5  to  12  mm.  in  diameter.  Spicule  single,  5  to  6  mm.  long.  Vulva  near  the 
anterior  end  of  the  body.  Eggs  64  to  68  ft  long  by  40  to  44  ft  wide,  thick- 
shelled,  with  pitted  surface.  In  kidneys,  ureters,  peritoneal  cavity,  or 

bladder Dioctophyme  visceralis.3 

Male  10  to  11  cm.  Greatest  diameter,  650  fi.  Tail  twisted  in  a  loose  spiral 
with  a  pointed  end;  8  pairs  of  papillae,  4  preanal  and  4  postanal.  Spicules 
unequal,  the  longer  215  ft  long,  25  fi  broad,  with  a  membraneous  extension 
70  fi  long.  Short  spicule  140  fi  long,  52  ft  broad.  Female  20  to  21  cm.  long. 
Vulva  600  fi  from  the  anterior  extremity.  Anus  300  fi  from  the  posterior 
extremity.  Eggs  ovoid,  45  by  26  ft  when  fully  developed.  Viviparous. 
Parasitic  in  the  peritoneal  cavity Setaria  bernardi. 

1  Railliet  and  Henry,  1911,  describe  a  new  species,  Filaria  bauchei,  found  in  the  "lungs  "of  a  hog  slaughtered 
at  Hud,  Indo-China.  The  location  of  the  parasite  is  not  definitely  known.  The  female  alone  was  found. 
It  is  reported  as  22J  cm.  long,  with  a  maximum  diameter  of  635  ft.  The  body  is  transversely  striated,  the 
striae  being  5  to  6  /» apart.  Mouth  unarmed,  funnel-shaped,  the  cuticle  thickened  at  the  anterior  end.  Anus 
155  p.  from  the  posterior  extremity;  vulva  1. 1  mm.  from  the  mouth. 

8  GigantorhynchtLS  Tiirudinaceus,  although  normally  located  in  the  intestine,  sometimes  perforates  the 
intestinal  wall,  in  which  case  it  may  be  found  in  the  peritoneal  cavity.  (See  No.  2  of  this  key,  first  para- 
graph.) 

Ascaris  suum  may  be  found  aberrant  in  various  locations  outside  the  digestive  tract.  Diagnostic  char- 
acters for  the  identification  of  this  species  have  already  been  given.  (See  No.  2  of  this  key,  second 
paragraph.) 

*  Included  by  Von  Linstow  (1878a)  among  the  parasites  of  the  domestic  hog,  but  its  occurrence  in  this 
host  is  questionable. 


THE   EOUNDWORMS   OF   DOMESTIC   SWINE.  41 

CLASSIFIED    LIST    OF    ROUND  WORMS    PARASITIC    IN   DOMESTIC 

SWINE. 

Specific  descriptions  are  omitted  from  the  following  list  as  these 
have  already  been  given  in  the  key  to  the  roundworms  of  swine. 
Arranged  according  to  their  respecive  orders,  families,  and  genera, 
the  roundworms  reported  as  parasitic  in  domestic  swine  are  as  follows: 

Class  Nemathelminthes:  Cylindrical  worms  without  a  prebuccal  ciliary  apparatus 
provided  with  a  variable  nervous  system,  not  forming  a  ventral 
chain.  Generally  dioecious. 

Order  Nematoda.     Nemathelminthes:  Provided  with  a  complete  digestive  tube. 
Family  Angiostomidae.     Nematoda:  Having  two  heterogenetic  generations, 
one  of  free-living  males  and  females  and  one  of  hermaphroditic 
or  parthenogenetic  forms  which  are  parasitic. 

Genus  Strongyloides.  Angiostomidse :  Parasitic  form  with  mouth 
opening  directly  into  the  relatively  very  long  subcylindrical 
esophagus.  Vulva  posterior  of  the  middle  of  the  body.  Uterus 
double.  Two  ovaries.  Free-living  form  with  mouth  opening  into 
a  vestibule  or  pharynx,  followed  by  an  esophagus  whose  anterior 
portion  is  fusiform  and  posterior  portion  globular. 

Strongyloides  suis. 

Family  Gnathostomidae.     Nematoda:  Body  furnished  throughout  its  length, 
or  only  anteriorly,  with  chitinous  blades  or  wings,  serrated  posteri- 
orly.   Head  subglobular,  covered  with  simple  spines. 
Genus  Gnathostoma:  With  the  characteristics  of  the  family. 

Gnathosloma  hispidum. 

Family  Trichinellidae.  Nematoda:  Esophagus  consisting  of  a  chain  of  single 
cells,  the  lumen  of  the  esophagus  passing  through  the  center  of 
each  cell.  Anterior  portion  of  body  containing  the  esophagus 
usually  very  slender;  posterior  portion  containing  the  intestine 
and  reproductive  organs  more  or  less  swollen.  One  testicle,  one 
ovary. 

Subfamily  Trichinellinse.  Trichinellidae :  Male  without  spicule.  Female 
ovo viviparous.  Adulte  in  intestine  of  host  produce  larvae  which 
penetrate  into  the  muscles,  become  encysted,  and  develop  to 
maturity  when  the  flesh  of  this  animal  is  eaten  by  another  animal. 
Genus  Trichinella.  Trichinellinse :  Very  small  worms  with  capillary 
bodies.  Progressively  increasing  in  diameter  posteriorly.  Male 
with  two  conical  posterior  appendages  forming  a  copulatory  bursa. 
Vulva  of  the  female  in  the  anterior  fifth  part  of  the  body. 

Trichinella  spiralis. 

Subfamily  Trichurinse.  Trichinellidae:  Male  with  spicule.  Female 
deposits  eggs  characterized  by  the  presence  of  an  opening  at  each 
pole  closed  by  a  pluglike  operculum.  Egga  do  not  hatch  until 
swallowed  by  a  suitable  host.  Development,  so  far  as  is  known, 
direct,  without  an  intermediate  host. 

Genus  Trichuris.  Trichurinae:  Anterior  portion  of  body  very  long 
and  slender.  Posterior  portion  of  body  containing  the  intestine 
and  reproductive  organs  relatively  thick  and  much  shorter  than 
the  anterior  portion.  Posterior  portion  of  male  rolled  dorsally 
into  a  spiral.  Spicule  surrounded  by  a  prepuce-like  sheath. 
Posterior  portion  of  body  of  female  slightly  curved.  Vulva  near 
the  beginning  of  the  posterior  portion  of  body Trichuris  suis. 


42  THE  ROUNDWORMS  OF   DOMESTIC   SWINE. 

Family  Filariidte.  Nematoda:  Body  long,  filiform.  Mouth  surrounded  with 
papillae,  or  provided  with  two  lips.  Esophagus  slender,  without 
posterior  bulb.  Males  with  two  unequal  spicules  (sometimes  with 
a  single  spicule).  Females  with  two  ovaries.  Vulva  usually 
anterior  of  the  middle  of  the  body.  Development  often  requires 
an  intermediate  host. 

Genus  Filaria.  Filariidae:  Body  long  and  slender,  of  nearly  uniform 
diameter  throughout;  males  considerably  smaller  than  the  females, 
with  the  tail  hooked  or  curved  in  a  spiral,  sometimes  furnished 
with  lateral  wings.  Usually  there  are  four  preanal  and  a  variable 
number  of  postanal  papillae.  Spicules  usually  very  different  in 
shape  and  dimensions.  Vulva  more  or  less  near  the  mouth. 

Filaria  bauchei. ' 

Genus  Setaria.  Filariidae:  Head  armed  with  a  projecting  peribuccal 
circle,  deeply  notched  laterally,  somewhat  less  indented  dorso-ven- 
trally,  giving  the  impression  of  two  teeth  when  seen  laterally  and 
of  four  teeth  when  seen  at  an  angle.  Tail  of  both  sexes  provided 
with  two  special  appendices Setaria  bernardi. 

Genus  Gongylonema.  Filariidae:  Body  filiform,  slightly  attenuated 
at  either  end.  Anterior  portion  of  body  covered  with  numerous 
tubercles  or  shields  formed  by  differentiation  of  the  cuticle.  In 
the  median  lines  immediately  behind  the  mouth,  two  semilunar 
depressions,  one  dorsal,  the  other  ventral.  Tail  of  male  curved 
ventrally,  supplied  with  two  asymmetrical  membranous  wings. 
Vulva  a  short  distance  anterior  of  the  anus.  .Gongylonema  scutatum. 3 

Gongylonema  pulchrum. 

Subfamily  Arduenninae.  Filariidse:3  Mouth  with  two  lateral  lips  leading 
into  a  pharynx  marked  with  cuticular  ridges  in  the  form  of  spirals 
or  rings.  Spicules  unequal,  the  longer  several  times  the  length  of 
the  shorter.  Four  pairs  of  preanal  papillae.  Eggs  containing 
embryos  at  the  moment  of  ovi position. 

Genus  Arduenna.  Arduenninae:  Mouth  leading  into  a  cylindrical 
pharynx  marked  by  ridges,  forming  a  continuous  multiple  spiral. 
Esophagus  continuous,  nearly  one- third  of  the  length  of  the  body. 
Spicules  very  long  and  very  unequal.  Tail  twisted  in  a  single 
coil.  Bursa  asymmetrical,  supported  by  five  pairs  of  papillae. 

Arduenna  strongylina. 
Arduenna  dentata. 

Genus  Physocephalus.  Arduenninae:  Body  furnished  anteriorly 
with  six  lateral  wings  arranged  in  a  group  of  three  wings  each,  on 
either  side.  The  middle  wing  of  each  group  is  the  widest.  Pharynx 
cylindrical,  relatively  broad  and  long,  marked  with  a  simple  spiral 
ridge  on  the  inside,  breaking  up  into  separate  rings  and  resuming 
the  spiral  at  the  posterior  end Physocephalus  sexalatus. 

Genus  Simondsia.4  Filariidae:  Female  characterized  by  a  tegumen- 
tary  excrescence  in  the  form  of  a  rosette  situated  in  the  posterior 
part  of  the  body  and  inclosing  a  prolongation  of  the  intestine  and 
a  hypertrophied  uterus Simondsia  paradoxa. 

i.This  species,  described  by  RailHet  and  Henry  (1911),  is  provisionally  included  in  the  genus  Filaria, 
sensu  lato.  As  only  one  female  was  received,  the  material  was  insufficient  for  a  more  accurate  generic 
diagnosis. 

*  Sec  footnote  2,  p.  39. 
^  » See  footnote,  p.  9. 

«  Railliet  and  Henry  (1911b)  include  Simondsia  In  the  subfamily  Arduenninne,  although  Piana  (1897e) 
describes  the  lips  as  dorso-ventral  rather  than  lateral.  In  the  structure  of  the  esophagus,  the  number 
of  preanal  papillae,  and  the  inequality  of  the  spicules  Simondsia  conforms  to  the  description  of  the  sub- 
family Arduenninse. 


THE   ROUNDWORMS   OF   DOMESTIC    SWINE.  43 

Family  Strongylidae.  Nematoda:  Head  with  eix  more  or  less  distinct  circu- 
moral  papillae.  Males  with  a  more  or  less  well-developed  bursa, 
each  lateral  lobe  of  which  is  usually  supplied  with  six  supporting 
rays.  Spicules  equal  or  subequal.  Vulva  may  be  anterior  to  the 
middle  of  the  body,  but  is  usually  posterior.  Oviparous.  De- 
velopment, so  far  as  known,  direct  without  intermediate  host. 
Subfamily  Strongylinae.  Strongylidse:  Buccal  capsule  well  developed. 
Eggs  in  the  process  of  segmentation  at  the  moment  of  oviposi- 
tion.  Embryo  nearly  always  rhabditiform  and  development  di- 
rect. Parasitic  in  the  alimentary  canal;  exceptionally  in  the  res- 
piratory system. 

Genus  (Esophagostomum.  Strongylinae :  Head  75  p  or  more  in  diam- 
eter; buccal  capsule  small.  Cuticle  surrounding  the  mouth  usually 
inflated  to  form  a  ringlike  mouth  collar.  Bursa  of  male  with  two 
lateral  lobes  united  by  a  smaller  median  lobe.  Spicules  more  than 
0.5mm.  long,  slender,  tubular,  pointed ;  gubernaculum  present,  but 
not  conspicuous (Esophagostomum  dentatum. 

Genus  Globocephalus.  Strongylinse:  Buccal  capsule  cylindrical, 
larger  in  diameter  than  the  thickness  of  the  body,  supported  by 
two  chitinous  rings— one  at  the  anterior  end  of  the  capsule,  the 
other  at  the  posterior  end.  The  rings  are  joined  by  four  chiti- 
nous longitudinal  bands Globocephalus  longemucronatus. 

Genus  Crassisoma.  Strongylinse:  Buccal  capsule  oval,  smaller  in 
diameter  than  the  thickness  of  the  body,  supported  by  eight  longi- 
tudinal thickenings  of  the  cuticle,  and  a  chitinous  ring  on  the 

inside  of  the  capsule Crassisoma  urosubulatum. 

Subfamily  Trichostrongylinse.  Strongylidae :  Buccal  capsule  absent  or 
slightly  developed.  Eggs  generally  segmenting  at  the  time  of 
oviposition.  Embryo  rhabditiform  and  development  direct. 
Parasitic  in  the  alimentary  canal. 

Genus.    Undetermined  » Strongylus  rubidu*. 

Subfamily  Metastrongylinse.  Strongylidse :  Buccal  capsule  absent  or 
slightly  developed.  Eggs  in  various  stages  when  oviposited. 
Embryo  rhabditiform.  Evolution  unknown,  perhaps  requiring  an 
intermediate  host.  Parasites  of  the  respiratory  or  circulatory 
system. 

Genus  Metastrongylus.  Metastrongylinae:  Mouth  with  six  lips. 
Postero-lateral  ray  much  reduced  or  absent.  Dorsal  ray  and 
externo-dorsal  rays  slender,  the  others  thick.  Two  very  long 
spicules.  Vulva  close  to  the  anus.  Eggs  with  well-developed 
embryos.  Parasitic  in  the  bronchi  and  trachea. 

Metastrongylus  apri. 

o  ,  ,      .,  Metastrongylus  brevivaginatus. 

bubfamily  not  determined. 

Genus  Stephanurus.  Strongylidae:  Anterior  extremity  truncated; 
mouth  suborbicular,  limited  by  a  chitinous  ring  furnished  with 
teeth.  Caudal  bursa  of  male  with  many  lobes. 

Stephanurus  dentatus. 

1  See  footnote  1  on  p.  39. 


44  THE   ROUNDWORMS   OF   DOMESTIC   SWINE. 

Family  not  determined.1 

Genus  Dioctophyme.  Nematoda:  Body  cylindrical,  mouth  without 
lips,  surrounded  by  papillae.  Male  furnished  with  a  filiform 
spicule.  Female  with  a  single  ovary.  Vulva  in  the  anterior  part 

of  the  body Dictophyme  visceralis. 

Family  Ascaridae.  Nematoda:  One  lip  median,  dorsal;  two  submedian, 
ventral.  Relatively  thick  forms.  Males  provided  with  two 
spicules.  Females  with  double  ovary. 

Genus  Ascaris.  Ascaridae:  Furnished  with  three  strong  lips,  the 
lateral  sides  of  which  are  generally  toothed.  Males  with  two  equal 
or  subequal  spicules  and  numerous  papillae  anterior  and  posterior 
of  the  anus.  Vulva  located  anterior  of  the  middle  of  the  body. 
Eggs  globular  or  ellipsoidal,  usually  surrounded  by  an  albu- 
minous envelope.  In  process  of  segmentation  at  the  time  of  ovi- 

position Ascaris  suum. 

Order  Acanthocephala.     Nemathelminthes  without  mouth  or  digestive  tube. 

Furnished  with  a  protractile  proboscis  armed  with  hooks. 
Family  Gigantorhynchidae.    Acanthocephala:  Body  large  and  annulated; 
taeniaform.     Hooks  of  the  proboscis  with  two  roots  and  covered 
with  a  transparent  layer  of  chitin.     Lemnisci  lengthened  into  the 
form  of  rounded  bags  and  having  a  central  canal. 
Genus  Gigantorhynchus;  with  the  characteristics  of  the  family. 

Gigantorhynchus  hirudinaceus. 

i  Dioctophyme  visceralis  although  commonly  included  in  the  family  Strongylidse  does  not  conform  to  all 
the  characteristics  of  this  family.  It  more  closely  resembles  the  Filariidae  as  pointed  out  by  Raillet  and 
Henry  (1909a).  Probably  it  should  be  placed  in  a  family  by  itself,  but  the  question  is  open  to  further  study. 


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THE   ROUNDWORMS  OF   DOMESTIC   SWINE.  47 

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